The best thing to do is find a donor car and buy it just for the transmission. You can get the five speed out of an 850 NA. There is quite a bit of information about this on volvospeed.com.

I would like to hear more about the 68 Chevelle?The first car I ever bought for myself while in the Navy was a 69 Chevelle Malibu with a 350, 3 speed Muncie shifter on the floor, two barrell carburator and single exhaust. Doesn't sound like much, but it ran right with the SS-396 for some reason. I blew the doors off a Plymouth Gold Duster with a 340 in it one time, and the guy called me a liar when I told him what I had in it. His was all jacked up with square dual exhauts and a big old hood scoop and mine was a real sleeper. We actually pulled off the road and I opened my hood for him. He still couldn't believe I beat him, so I beat him again when we pulled out of the parking lot. Sucker had posi-traction so it got off the line real good without laying a lot of rubber. It did lay some rubber though.