What i'm trying to say is that unless the engine is built enough that the fuel injection wont work, there is no benefit to a carb. It will be worse in fact. You couldnt pay me to take a carburetor on a vehicle anymore. Its bad enough you have to put up with them on lawn mowers and such.
It will probably be easier and cheaper to modify the TBI to work with what you have, assuming it wont work as is. Alot of times you can just change the programming in the ECM and youre done. Other times you need bigger fuel pumps, bigger injectors, adjustable fuel pressure regulators etc on top of changing the programming. In that case a carb might be easier and cheaper but either way youd be looking at alot of work.
The way I understand it you are wanting to use the stock tbi fuel pump and regulate it down to carb fuel pressure (which if i recall right isnt a big drop - i dont remember TBI having much more than carb fuel pressure anyways) which tells me the engine is atleast close to stock. Otherwise that pump couldnt supply enough fuel. I would think you could get away with changing the programming in the ECM and be done.