Here is a thread that I was involved in with a lot of good ref's and replies.One thing in summary that I think I found out about the caddy engines is in stock form the valve train/heads are fine,but if you want more the after market gets expensive.Also they are not a high rev'ing engine.

Read threw the links and I think you will see what I am talking about.

http://clubhotrod.com/forums/showthread.php?t=44826