Can anyone tell me please......... how much more would the wheel rim on a reverse offset wheel stick out compared to a standard one - if it makes any difference the wheel in question would be a 15*8 cragar SS.
It was called "reverse" years ago with the advent of "chrome reverse" wheels. It's slang, like "3/4" cam.
Truly, there is no standard offset on regular wheels and no fixed offset for "reverse" wheels. You need to measure offset on both wheels to determine the differences and how they will fit.