Check this out.
http://www.thirdgen.org/techboard/tb...-using-gm.html (Who is atually using a GM 454 TBI unit on a SBC?)
The dctrumpet is a board member & e-bay power seller of throttle body
parts.
I decided to keep the TBI control system in place, and upgrade
the throttle body, and ECM. I hope to get it running next year.
There's lots of good info available here, so get ready to read a lot.
Expertise is also available, but can be a bit persnickety if the answers
are available from the stickies.
In summary, the TPI system is intended for torque, and falls flat above
5500k. TBI has some versatility advantages, like manifold options,
but is rather capacity limited -- 650 cfm is pretty much a structural limitation.
Good luck, and keep us posted.