Detail preserving upscale aspect ratio issue

Question

My goal is to take a 720x480 60i DV file (non square pixel) and upscale to 960x720 60p square pixel for YouTube upload.
My workflow seems to work, except I'm not quite getting the correct aspect ratio at the end. I'm getting an extra 5 pixels on the bottom and top of my image so it's being squished by a total of 10 pixels. I have uploaded a screen capture to demonstrate this. In case the image preview doesn't work here's a Flickr URL:
https://farm9.staticflickr.com/8623/16158021066_e52966ff22_o.jpg
On the left is a simple AE scale, I dragged the DV file into a timeline, and used the scale command to change the pixel resolution to 960x720 so the DV file stretches to fill the 4:3 frame as it should. Remember, I'm trying to get the DV file to square pixel aspect ratio for online viewing. On the right is the result of my workflow below using AE CC and detail preserving upscale. The 5 pixel gray bars are part of the movie file.
Import the DV master into After Effects CC
Right click the file in the project bin, go to Interpret footage, then MainSet Conform frame rate to 59.94, hit okay
Drag this movie to the new composition button
Select the composition in the project bin, hit Command+K to open the comp properties
Set the frame size to 960x720
Set the duraction to double the original
Set pixel aspect ratio to square, hit okay
Select the video layer in the new comp, then go to the Layer menu, select Time, then Time Stretch and enter 200, then hit okay, the number should match the frame duration you just got from doubling the original
Now, add the Detail preserving upscale effect
Click fit width
Export

Answer 1

Thanks for the reply Mylenium. Typically I do separate operations like this using pre-composing but I found it made no difference so I removed that step in my original workflow so save work.
I'm not sure what "crooked HDV/ IMX values" means, can you elaborate?
If you mean my frame size of 960x720 this is the minimum that YouTube will need for a 4:3 video to generate a 60p video. They don't want 4:3 videos encoded in 16:9 wrappers and they have good reasons for this.
I'll say for the sake of simplicity to forget all about the 60p conversion here and focus on the 4:3 non square PAR conversion using the DPU (detail preserving upscale). I was able to accomplish this but it requires me re-scaling the video in After Effects first... to either 640x480 or 720x540 square pixel... but I'm just trying to avoid this additional scaling operation.