1991 Chevy Truck Throttle body injection change over to a C

WHY? TBI is more efficient, gives better starts and is much better than any carb.

You would be looking at a pretty good list of items as well. Different fuel pump or inline regulator, The correct carb to work with a different computer. The biggest thing is that it would violate the law as well unless you never drive it on the road. It is considered tampering with the emissions controls.

Just because it isn't the answer you wanted doesn't make it wrong. It is a fact that converting the way you want is illegal.
It is also a fact that the conversion is a PIA. You basically need to change out half of the fuel system, the computer, the wiring harness in the front.