Need help with tire size and lowering and traction..

[smoknbarrels]

Hey there,
I am just getting into the phase of lowering my '67 long box fleet side with a 454. I am thinking of lowering it 4 front 5 rear. can anyone tell me what is the max tire size i can fit in this configuration? and I was planning on going with 8" rims front and 10" rear.. any idea what back spacing will be needed to optimise at least a 295 tire in the rear?? which leads to my last question.. will i get any traction running 550HP, or am i just wasting my time?
should I just tub it and use mickeys??