Google Howell Engine Developments. They make all kinda of factory type TBI, MPFI and other fuel injection setups. And compared too all the aftermarket kits out there (holley, edelbrock, fast efi). I have an 89 TBI system with ac, trans torque converter lock up, and no timing control distributor and the system has operated flawlessly since I put it on over 6 months ago. I love it. I do recommend if you get one to include the timing control distributor portion of the system, I didn't but I'm considering adding it on.
You said your going to get an HEI distributor any, the TBI disti's are HEI, they just have a coil that is seperate from the disti cap.
Call them, tell them what your doing, they can build you a pretty nice setup. My truck has over 360hp, 400+ ft lbs trq and the TBI system handles it great.
Howell, (810)-765-5100.