How can I reset my macs partition map?

Question

I have an MBP mid 2012 with 750GB HD (the higher model, with i7 2.9GHz and 8 gigs of ram) which I am possibly passing on to someone. I have the latest version of Mavericks, triple booted to include Windows 8.1 and Linux Ubuntu.
To reset the computer I will likely use this method:
Step One - Back up your data:
       A. If you have any Virtual PCs shut them down. They cannot be in their "fast saved" state. They must be shut down from inside Windows.
       B. Clone to an external drive using using Carbon Copy Cloner.
          1. Open Carbon Copy Cloner.
          2. Select the Source volume from the Select a source drop down menu on the left side.
          3. Select the Destination volume from the Select a destination drop down menu on the right
              side.
          4. Click on the Clone button. If you are prompted about creating a clone of the Recovery HD be
              sure to opt for that.
               Destination means a freshly erased external backup drive. Source means the internal
               startup drive.
Step Two - Prepare the machine for the new buyer:
          1. De-authorize the computer in iTunes! De-authorize both iTunes and Audible accounts.
          2, Remove any Open Firmware passwords or Firmware passwords.
          3. Turn the brightness full up and volume nearly so.
          4. Turn off File Vault, if enabled.
          5. Use Boot Camp Assistant to remove a Windows partition, if there be one.
          6. Disable iCloud, if enabled: See.What to do with iCloud before selling your computer
Step Three - Install a fresh OS:
     A. Snow Leopard and earlier versions of OS X
          1. Insert the original OS X install CD/DVD that came with your computer.
          2. Restart the computer while holding down the C key to boot from the CD/DVD.
          3. Select Disk Utility from the Utilities menu; repartition and reformat the internal hard drive.
              Optionally, click on the Security button and set the Zero Data option to one-pass.
          4. Install OS X.
          5. Upon completion DO NOT restart the computer.
          6. Shutdown the computer.
     B. Lion and Mountain Lion (if pre-installed on the computer at purchase*)
         Note: You will need an active Internet connection. I suggest using Ethernet if possible because
                   it is three times faster than wireless.
          1. Restart the computer while holding down the COMMAND and R keys until the Mac OS X
              Utilities window appears.
          2. Select Disk Utility from the Mac OS X Utilities window and click on the Continue button.
          3. After DU loads select your startup volume (usually Macintosh HD) from the left side list. Click
              on the Erase tab in the DU main window.
          4. Set the format type to Mac OS Extended (Journaled.) Optionally, click on the Security button
              and set the Zero Data option to one-pass.
          5. Click on the Erase button and wait until the process has completed.
          6. Quit DU and return to the Mac OS X Utilities window.
          7. Select Reinstall Lion/Mountain Lion and click on the Install button.
          8. Upon completion shutdown the computer.
But, due to having three partitions on my computer and multiple operating systems installed, I at some stage needed to mess with the partition map (I remember doing this at one point: Repairing Boot Camp after creating new partition). Will using the above steps completely reset any custom "bios" I had installed and reset the partition maps/remove all partitions (Assuming I likely delete all the partitions and then re allocate all the space to OSX?
And if the above would not work, what do I need to do to remove these and will it be possible to restore the mac fully to the "factory default"?
Thanks,

Answer 1

So this will completely overwrite any of the steps in this process?
sudo gdisk /dev/disk0
If you get any error messages at this point, report the error messages, don't proceed further.
You're now in gdisk interactive mode. Menus/commands are single characters followed by return/enter. So type ? and <enter> and you'll get the main menu listing commands. Type p <enter> and it will print (display) the current GPT. Since you have 5 GPT entries, you can't use a 1 for 1 GPT to MBR scheme like Apple does. The following suggestion is safe, but all hybrid MBRs are non-standard inventions, and therefore I can't tell you how Boot Camp Assistant or Disk Utility will react to this hybrid MBR should you decide to make changes later. What I can tell you is Windows, Linux, and Mac OS X themselves have no problem with this MBR scheme.
r <enter>        go to the recovery & transformation menu
h <enter>        create a new hybrid MBR
5 <enter>        add partion 5 to the MBR
<enter>          accept the default MBR hex code of 07
y <enter>        set the bootable flag
n <enter>        do not protect more partitions
o < enter>       print (display) the MBR
You should have two entries. One type EE, one 07, with the 07 entry marked with * under Boot. If you don't, report back. If you do, write out the update partition information, and hope  a power failure doesn't occur for the next few seconds...
w <enter>     write partition table to disk
reboot. hold down option - you should be able to boot into either Mac HD, Recovery HD, or Windows.
I just tested this same five partition GPT and 2 partition MBR on a working system and the instructions above worked.
Note, so long as CSM-BIOS and thus MBR are required for Boot Camp instead of EFI booting Windows, we're stuck with flaky MBR problems, as well as the 2TB disk limitation for Windows boot disks.
If so, problem solved, thanks!