I ran Richmond 3.55's in my 31 Model A coupe and my 65 Fairlane. Both cars run a warm 351C. They are still doing fine. Powertrax makes a locker for the 8" that's supposed to be good. There was an instl article in a back issue of Street Rodder.
All the aftermaket 8" gears are basically equal and they all are stronger than the 8" caps(will break and push ring gear out the back) and pinion mounting surface on older single ribbed 8" carriers(will yank the pinion out the front with front of case still bolted to pinion support from weak case). The strength of the gears are the last thing to worry about. I have pulled the pinions thru the front breaking the case and the front of case comes out as one piece with pinion and pinion support on launch and also pushed the ring gears thru the caps many times on launches that were in the 1.40s. The pinion being yanked thru the front was on one old style single ribbed case I had and learned not to use those early cases anymore.