8 3/4 gears

70dart340 said
Hello, all. I have a spare 8 3/4 complete rear end for my '70 Swinger 340. I'm building a stout 408 for her, and it's time to consider the rear assembly. I have a small yoke 741 with a 3.23 SG rear assembly. I have a couple of questions:
Can I replace it with a 742 or 489 SG, or is this overkill?
All the rear disc conversions seem to require 15" wheels. I know Summit has 15" wheels in the SBP, is this the way to go?
Green bearings, or Timken tapered?
Will my stock axles handle about 480HP at the wheels, or do I need to upgrade?
I'm making this like a FAST car, I want to look stock if you pull up next to me.
Thanks to all ahead of time for the fountain of knowledge about to come. Paul.

I have a 408 in my '70 Duster with a similar rear as you. Had a local guru build my third member. I had issues with the axle seals leaking (replaced them and leaked again) and ruining the brakes so ordered axles (BBP) with green bearings from Dr Diff. Those bearings have an O-ring that positively stopped the leaking. Upgraded the rear brakes to the larger size at the same time & upgraded the front disc brakes using the Dr. Diff BBP disc kit. Used the OE non-power master cylinder. No issues whatsoever with running that rear. The wheels are 15x8 on the back and 15x7 on the fronts. Tires are 275/65r15 back and 215/60r15 on the front with BFG.

Edit: Ordered OE style rallye wheels but canceled the order after waiting 9 months with no ETA for them. Went with BBP vision wheels all around.