Hi my name is Ron. My first car was 1974 Apollo 2 door 3 on the tree behind a chevy 250 inline 6. Of coarse I wish I still had it and of coarse I could not leave it alone. I got a used Muncie 4 speed and put it in. It bolted right up , I did not have to change the drive shaft, I did put a hole in the floor for the stick. Never had any trouble with it. Note: I did start with a stick car, as far as bolting it to a buick 350 you can use a BOP bell housing or get an adapter plate that you can bolt a chevy bell housing to a buick block, the adapter is thin enough it does not affect the drive shaft length. If you are starting with an automatic car, you will need the pedal assembly, you can use them out of 73-74 novas, venturas, gtos, and omegas, all are x-body cars. A neat little fact NOVA has been around since the early 60s, they came up with the names for the x-bodies except for the 74 gto, from NOVA: Nova,Omega,Ventura,Apollo. I hope my experience helps you with your questions thanks.
The Nova pedal and clutch pedal stuff should bolt up under the dash. Whether it is 68 - 74, or 75 - 79.
To answer your question...yes. The Saginaw is a good street trans and I have my doubts as to whether any Muncie is better if It is not an M-22 or modified for racing. The best Saginaws to get your hands on have three grooves on the input shaft. These have a low first gear and close ratio. Using the factory bellhousing,you should be able to reuse driveshaft,crossmember,and rear mount.