I have used the 70's corvette rally 8" wide wheels and they fit very well.
A buddy of mine just used a set on his 69 camaro for track use and is very pleased.
He used to use 7" X 15 alloy rims but cracked one.
I'd been telling him for years to get those 7" wide rims off and use the 8".
A 10" wide is really hard to fit due to the inside offset needed to get it in there.
Most old style 8.5" aluminum wheels like the 200S or torque thrust have too much positive offset.
Newer versions have more neg offset and I think an 8.5" wheel with 4.5 to 4.75" backspace is real good. I would favor the 4.75" and use a spacer if the wheel needs to move out a little.
Third gen wheels like the IROC or Trans Am are pretty close, but might have a bit too much neg offset.
The third gen Z/28 wheel is good but only 7".
A 225X50X15 is probably getting near the limit without more backspace or mods.
I've heard of wider tires on the rear but don't know the mods used to get them on.
BFG has some great rear drag tires and I've heard the handling isn't bad either.
The G force road race type tires are good too, but not much tread on them.
Check my web page for First Gen Camaro suspension info:
David's Motorsports page
First Gen Suspension Page
67 RS 327
69 Camaro Vintage Racer
65 Lola T-70 Chev 350 Can-Am Vintage Racer
[This message has been edited by davidpozzi (edited 11-24-2001).]