Both the T 10 and Muncie are side shifted.
To the OP: to get a Muncie guaranteed in good shape; is going to cost you over a grand; then you need a clutch/pressureplate, flywheel, clutch linkage, bellhousing, throwout bearing, perhaps a new crossmember. Lets not forget the pedals and any linkage there.
We just built a gearbox for a former Lemans car; new case, iron midplate, italian gears and synchronizers, everything new, not one Muncie OEM part; and it was $2275. I've seen our basic transmissions go used for 1200 bucks. I've also seen our Supercase filled with worn out original gear sell for a grand as well. You really need to know what you are looking at when you buy a manual trans; and I'd really hesitate to buy sight unseen because with your budget, you can't afford to get screwed, even if you have to pay a little more to get exactly what you want.
My advice? Get a TH350 or 700r4 core and rebuild it yourself; and save your money for the Muncie/T10 conversion. Plan on 2 grand unless you get a donor car or someone going to a 6speed.
The key to being a young guy with a hot rod is keep it simple, keep it basic and keep it running.
If you want to build your own Muncie; Start with a new Muncie case and go from there. I can help you find good used parts, or people who rebuild em using good parts