Here's a tip that has always worked for me--when you put everything together for the first time, take the solenoid off of the starter, bolt the starter up, and pull the Bendix into engagement with the flywheel teeth. You should just be able to slide a thick paper clip between the high point of the Bendix tooth and the low point between the flywheel teeth. This will tell you if it needs shims, or if you have the wrong starter and it engages too deeply. Beware, there are 2 different versions of the 'straight-pattern' and 'staggered pattern' starters. Some starters had cast-iron noses and they will engage diffferently from the aluminum-nosed ones.
I've found that as a rule, if you buy an aftermarket 168-tooth flywheel it'll be already drilled for 10-1/2" and 11" pressure plate patterns, and the standard 168-tooth starter will work fine. If you go the original GM route, you could run into problems.
Also, be sure you know the spline of the input shaft of the Muncie--if it's an M-22 it'll have a different spline than an M-20 or M-21 and you'll run into clutch disc compatibility. Also, different pressure plates use different-length throwout bearings--flat diaphragm, cone diaphragm, 3-finger type, Borg & Beck...
I don't mean to make it sound so complicated--but this is stuff you could run into. For my 2 cents, I'd call Summit or Jeg's and talk them. They know what they sell and what works with what, and they can set you up with a complete package right out of the gate.
Good luck!
