Different pinion angle question.

[68LSS1]

I should be getting my HOTRODSTOHELL kit this week and I have a question. I would like to weld this up with the 8.8 and install to the frame. Will the pinion angle change later with all the rest of the truck on the frame? I know that the rear won't. That's relatively stationary to the frame (except of course under a load). But as the rest of the front end is put on the truck (along with cab, bed, etc.) won't the angle of the trans yoke maybe change slightly? My thinking is that the suspension will "sink" a little on both the front and back as the truck is put back together. More so in the front. Say I set it up for a +1 degree at the rear and -2 degrees at the trans. (I disagree with running a 0 degree pinion angle). Well now that I'm typing it out I think that although the tail may move down, its angle will stay the same. What do you guys think? I haven't finished the motor mounts in case I need to tweak some here. I know I'll need to finish that first before welding the new saddles to the rear end but I'd prefer to do this one time only.