wheel backspacing ?

[lukky 71]

i have a 71 camaro that has not been cheater tub but the fenders lips have been rolled. i have done several measurements. what i want to put under the rear is the foose nitrous 2 wheels. my measurements show that a 18x10 with a 6" backspacing will work with the mickey thompson 28x12-18 sr tires. the tread is 10.6 and the section width is 11.6 . with the 6" backspacing the tire is center in wheel well and i have about 1/2 " between the fender and the spring. all i want to know is has anyone used these combination or something close so i will know im going in the right direction. these wheels are special order only and i dont want to screw it up. any help would be thankful.