68 camaro wheel questions

[brgable]

I'm restoring my 68 camaro and while at a car show I saw another 68 that had 18x11 wheels on the back. I've heard of people fitting 10" wheels without having to minitub the rear but this guy said he didn't minitub his car and the wheels had 6 3/4" back spacing. I'm looking at going with forgeline DS3 wheels 18x8.5 in the front and 18x10 or 11 on the rear if i can get them to fit with that back spacing without minitubing the rear. My question is has anyone ever used a wheel that large with that back spacing or something similar and did not have to minitub the rear? Thanks for the help.