Go to
GM Performance Parts, and look through the choices there. Once you find ones you like, copy down the part numbers and go to your GM dealer and they can give you cost and availability details.
You'll most likely want to look at the Small Block engines.
I know guys that have used the original steering column, but modified it to shift the automatic transmission (rather easy to do), so you would have the look of the three-on-the-tree but have a modern, reliable transmission. This would be my route.
