68 - 72 are the same 67 and back has a different idler, 73 and on use different motor mounts. So yes a 71 is the same and will bolt right in with 69 parts. 73 and up will fit but you will need the MOTOR mounts for it.
WOW....all over the place. I like your spunk. Be a bit more specific when you ask a question and you will get better answers. Here is some broad and general stuff.
6'rs unless special ordered were little ones...7's. Put a V8 ahead of one and hammer it and see the teeth break off......sweeet.
Ratios were spec'd unless it was a floor model.
2.9's in some cars...steeper in others.
Ex manifold may be issues as it was designed for an engine that sat a bit more forward....someone here will slay me if I'm wrong.
If you want to.....hang on a bit on the build and we can help you and save you $$$$ and frustration.