I want to know if this has been done before and what it involves. I would be looking to perform the swap on a 67 the originally had a 327 with a TH350(I think) in it.

Sure it has been done, prolly about a zillion times. :D well, maby not a Zillion! EC Parts, or the El Camino Store, has the complete pedal kit including everything down to the clutch fork, for about four hundred and something. Then you just need a tranny, Bell Housing, Flywheel, clutch/pressure plate, throw-out bearing and piolet bearing.

I think the Muncy mounts in the same place as the THD 350 and will use the same driveshaft. You'll need a new neutral safety switch or disconnect the one you have, if you have one. A reverse light switch. Possibly a reconfigured Drive and Driven gear for the Speedo.

It can be done and has been done. Should be fun to drive, except in rush hour traffic.