I'm no expert, but if you have to spend money rebuilding the TBI's, I think you'd be better off with the vortec's. They are the best bang for the buck. I did a 383 and didn't think twice about buying vortecs and turning the tbi's into boat anchors. One thing to keep in mind is the vortec's won't support a cam lift above .460 or so, without modifying them. Summit claims .520 lift with their version for the same price as GM's
I was playing with the CamQuest
program and changed nothing but the head specs and my motor went from 425hp all the way down to 357hp using the tbi head.
You can also google: vortec vs. tbi heads and get a pretty good idea of what folks think of them.