Reply to "Pantera 06927"

I'm glad you found a stock rotor, Robert. I don't check e-mails daily so I'm a bit late here.
1)-on rotor variations: Dennis Quella in Colorado Springs, CO sells ventillated rotors with an aluminum hat-section that fits over the axle flange front or rear. It obviously spaces the wheel and tire outboard by 3/8" or so. I run '69-76 Porsche 911 ventillated rear rotors with a home-made 1" thick aluminum hat section that fits behind the axle flange as-stock, but is 40% lighter. The vented 911 rear rotor has identical dimensions as stock. Some of the Swedish members did much the same using vented Volvo rotors and home-made spacers. Larry Stock of PPC-Carson City NV sells a Sierra brake conversion for front or rear that uses Porsche 911 rear rotors.
2)- due to the fact that the front bearing is captured between a counterbored step and a steel bolt-on retainer, the inner bearing position floats. So there is quite a tolerance for the inner tube spacer length: the inner bearing can move in or out as required. The only limiting factor is if the spacer gets so short from wear or constant 'squaring-up' with a lathe, that the inner companion-flange adapter for the u-joint bottoms out in the axle splines before you get enough torque on the nut to hold the assembly. Sorry- I've never calculated what that dimension might be.
As long as you're using std bearings, a near- stock spacer length should be just fine. The spacer ends need not be dressed perfectly flat; a few bumps etc won't hurt. On GTS or GR-3 club-racers that ran the optional 10" x 15" Campagnolo wheels and rather wide, sticky tires, DeTomaso used a double-row ball bearing at the inner position for better axle support. The only mod required was to shorten the spacer by the amount extra in the double row bearing. All else stayed the same.
Finally, once you get all this together again, be aware that all 16 bolts holding the halfshafts to the u-joint companion flanges must be tight. If one bolt or nut is even slightly loose, the assembly may yield a 'funny', untraceable vibration under heavy acceleration. If you feel such a thing, recheck those bolts & nuts first.