If you go with sticking with TBI I have a few recommendations.
First, peruse
GearHead EFI. The moderator there has a screen name of Dave W. (I think he may be a member here, too, but not sure if he's active) He also runs a business, Old School EFI, Vancouver, WA and is considered one of the most knowledgeable guys out there on legacy GM EFI systems (TBI, TPI, etc.) I would highly recommend getting in touch with him for recommendations on throttle body, injectors, and other stuff like EGR. In addition to the stuff already mentioned, you'll need a bigger TB, either 46 mm (what I'm using) or big block (I think 50mm) and bigger injectors. Stock 350 used 61 lbs/hr (65 for cop cars) - I'm using 80 lbs/hr from a big block, per Dave's recommendation. I agree with others on here that fuel pump should be upgraded, but Dave says it's probably not necessary - his tunes stay with stock pressure and the stock pump was the same for small and big blocks so it can handle the flow. BUT...just to be safe I did upgrade to a Walbro 190 which will be more than sufficient.
There are a number of other considerations that I'm not thinking of now. You can check out my build
thread, but it's kind of long.
Unfortunately, I'm not yet at a place where I can say how my setup actually works. Life happens...delayed yet again. New engine is sitting in the truck on its mounts, but nothing is hooked up yet and tranny's out right now. Should be able to start back up on it now and hope to have it running by August.