Sorry Chicago, my post was directed at the brokenparts the "thread jacker"
If you are doing the whole swap from the start, the vortecs are hard to beat out of the box since you can find them so cheap. When it comes to getting more performance out of them, the older gen 1 blocks are much cheaper to build. I like power so I would atleast go for the 6.0 and seriously consider the 8.1. (a few months back there was a great deal on an 8.1 over on pirate4x4)
TBI is definately cheaper, easier to work on and by the time you spend the money on the vortec harness and programming (if required), you could get a decent performance TBI engine with all of the compatability of gen 1 parts. If your happy with the performance of a stock vortec, then you would probably be better off going that route.
Either way I think you would be better off with a 4l60/4l60e.