Within a given case size, I haven't found the entry/exit pipe centerlines to be significantly different if they're the same center/offset design.
It can get tricky if you have to rotate a tailpipe a bit in a tight space and/or welded-on tips on an A-body.
I swapped 3 sets of mufflers on a '64 B-body trying to get the right sound, and it was easy.

Of my 2 Road Runners, the yellow one with a full restoration exhaust from Accurate is louder and crisper than the other (blue car) which is the same except for Dynomax Super Turbos.
Engine-wise, yellow has a bit more CR and slightly more aggressive cam specs, and the Decor Group chrome tips; both have stock exhaust manifolds.