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The numbers you are referring to are your wheel offset. The offsets can go either way (negative or positive) For instance, a a RWD car usually has a negative offset wheel, and a FWD car has a positive offset, in MOST cases. OEM wheels for my 85 have a 43MM positive offset, so they are basicly compatible with FWD vehicles. (don't ask me why) I guess the best way to explain it is, when you look at a typical RWD vehicle, the wheels have a concave look to them, and when you look at a FWD vehicle, the wheels look like they have a "flat" face. Hope this helps.
84-87 wheels are 36mm/38mm depending on whether you have 8.5" or 9.5".
88-96 17" wheels are 56mm, but i think the Grand Sports had something like a 50mm on the rear, but this is for the 11" wide wheels. ZR1s might have had something slightly different as well, but they should fit fine.
Anything very close to 56mm will fit perfectly. The 11" wide rears might stick out a little.