Dont even consider Tbi. If you have the budget I would go with port fuel injection, lots of them out there now, Edelbrock has nice stuff. Be ready for some tuning and diagnostics as most require a laptop and setup. I have used fast fuel injection in the past( throttle body injection) it worked well but was tricky to get right. The best fuel injection is a factory ls engine! Nice to see rb1 out and about!
what's your skill set? if you hate wiring like me (but clearly not me with the stupid wiring projects I take on) - FITech, Holley EFI or similar is a good system (I prefer the Holley, but just marginally). On the other hand, if you're a fruitcake and love wiring (not to disparage fruitcakes)* - any of the megasquirt systems are a good set up and very, very well supported by both the manufacturer and the EFI community.
as for cost, they really do all cost about the same.
*before you hatemail me - do check out my thread, specifically references to the 430 ci Buick turbo project (MS3x), the 64 Buick turbo project (MS3), and the FJ40 MS2 project..... lord, I'm a glutton for punishment.