Were it my car, I'd probably find a 3.09:1 gearset for the transmission and leave the 3.23s if they're not making any noise. More yee-haw off the line but old familiar friends in the next three gears. That being said, unless I'm looking for silly drag-strip/wheelie-poppin' gears, I try to get OE gears, either good used or NOS. There's never been a question of noise, and they're as durable--if not moreso--than the aftermarket stuff. Avoid Richmond's Pro series unless you plan on constantly dumping the clutch. They're a little softer to absorb extreme use/abuse, but they're not 50,000 mile gears. They wear more quickly, which Richmond clearly mentions.
I've built a few dozen 8.75" center sections and have always just used the rear shim (between the pinion head and the rear bearing) that came from the factory with the case I'm using (not the gears). I've never had reason to fiddle with the pinion depth doing that. Others may have not been so lucky.
