I know they have the same lug pattern, but I was looking at some welds and some have a 6.5 backspacing and some have a 7.5.
What would fit the C5 better? Does anyone know offhand?

 

i dont believe so since the offset might be different. they might stick out or tuck in too much. maybe someone can correct me if im wrong.

 

I don't know how much I'd worry about the bs as much as how much it will hit on your calipers. It depends on what size the wheel is 8, 10, or 12. I'm not sure what BS is necessary, but I think its the same as the fbody 8 in is 5.5 bs and 10 in is 7.5 bs. Probably want to check with a vette owner though.