Help before teardown!

[1967wannabe]

Finally gonna have some time this week to get going on the project and I'm looking for some help. First we'll be fitting up the a/m front 67 sheetmetal so that it can all be massaged to fit as it will all be painted apart. After that we'll strip it to the bare frame for powdercoat and I don't want to cut or grind on the frame after it's been powdercoated.
1) I'm dropping the rear 7" and I want to move the rear trailing arm crossmember back to center up the rear wheels in the wheel openings, how far back? 1"? Also, will the CPP notch have to be located 1" back and will the panhard bar develop any interference?
2) I'm using a CPP tubular LS mount kit to install late model 5.3/4L60E combo, I understand that the compressor will work but does the frame have to be clearanced with this kit? I've seen this combo done with the ECE kit without clearancing but unsure on the CPP kit.

Thanks!