Need backspacing advice

[bamafrost]

Have a '68 Fleetside with the stock 6 x 5.5" rims and stock rear end. A friend has a set of 6 on 5.5" 20" Torque Thrust rims that he's willing to sell me for $180 for the pair (they are new). They are good-looking, but have a 5.5" backspacing.

Will these work...or will they rub or create other issues? Thinking of running a 265 or 275 rear tire (either 45 or 50 aspect ratio). Would put matching 18/45-50/225 on the front (what Backspace would you recommend?)

Open to any and all input...thanks in advance for your help.

Also...would you convert front to 5 on 4.75 or 5 (converting to front discs right now)...or just stay with the 6 on 5.5" pattern all four corners. I know 6 on 5.5" lessens my rim choices. Would 6 lug on the back and 5 lug on the front make me a nerd? haha

Tom