Re: Moser a good choice? Or go S60?
For a "100% street car" like you've stated, any one of the rear ends will take 700 HP easy since you'll never get enough traction in first gear to break anything in the rear end anyway. Even with drag radial tires you'll be lucky if you can even use half throttle in first gear without tire spin. BTW the S-60 rear has mounting ears for the upper control arms that are 1.5" taller than the ears which were on the factory GM 12 bolt rear that I took out of the car. I installed the Strange Engineering S-60 in my Chevelle. It's nice to know I have 35 spline axles, and a 9.75" diameter ring gear back there, but it's a street/strip build, NOT a street only car like yours is.
The one negative thing about the S-60/Dana 60 rear is that the pinion seems to be higher than that of a Ford 9" rear. So if you ever decide to lower the ride height, it can get tougher to obtain the correct driveline angles for U-joint longevity with the S-60 rear. I had the S-60 rear delivered to me with the optional 11" diameter rear disc brakes installed, which was a nice add-on. I also chose the 5/8" diameter wheel studs, Big Ford housing ends, and the heavy support cover.
70 Chevelle SS clone (632 CI powered).