It looks like almost everybody is using TBI, I did come across somthing interisting the other day, I am working on a MPFI system for a Comanche that I plan to run at Bonneville. I was thinking of using a Megasquirt, but at the moment it does not support sequential spark or fuel. So i was looking at some of the aftermarket ECU systems, and finally seteled on using Haltech. But in working with them, I fount out that they have a computer that replaces the GM TBI computer. the model number is E6GMX. The advantage is that you don't have to screw around with eproms, and the computer will actually tell you whats going on. Here is a link to the info http://www.haltech.com/index.php?option=com_content&view=article&id=53&It emid=49
So if you already have a GM TBI system or even a wiring harness, you can plug this computer in and get a fully tunable system. It lists for about $890.00 but I am a dealer, so if you PM me i can probably help you out on the price.