454 Gear Ratio Advice Needed

[slaterson]

Hey all, recently bought a '68 SWB with a 1980's 350 and TH400, manual brakes and steering and no posi. My eventual goal is a big block 454 (or similar) with 500+ HP. mated to a Tremec T56 5 or 6 speed, possibly Holley EFI, posi rear end, power disk brakes (at least fronts) and power steering with air conditioning.

My goal for this spring is to add some nice wheels/tires and power disk brakes. Unfortunately, I have found a crap selection of 6 bolt wheels so I am planning to convert to 5 lugs. The local scrap yards have a good selection of posi rear ends but I am wondering which gear ratio would be best for my planned big block setup? Performance trumps fuel economy. Planning on 20" AR Torque Thrust wheels with 275/40 rear tires (not sure of total tire height). Also, would rear disks really be needed? .. Any other advice? ... Thanks, love the forum so far!