'64-'65 rear wheel size...

[classic]

You guys with tire/wheel knowledge on '64 to '65 Chevelles...

My '65 currently has 15 x7 cragar super stars with a 3.5 inch backspace and I only have 215 60/15's on the rears now. If I get a set of 15x8's with a 5.5 backspace, could I run a 255 60/15 on it and still have inner frame rail clearance between the frame and tire? Cragar quit making the wheel (apparently) but summit has them available in that size for $160 each. Bottom line, I want to run a 255 drag raidial on the rear if I can make it fit.

Thanks for your input! Greg