ive got a 1987 chevy c10 small block 350 with tbi..i hate it a buddy of mine is giving me a new manifold and a holley 750 for free and i was trying to figure out if the swap would work out..and what would i have to do Help please  

DON"T DO IT! Switching to a carb from TBI is a real pain in the butt, and doesn't make any sense performance wise.

Why do you want to get rid of your TBI? If you're having problems with it, what are they, might be easy to fix. I've got a '92 Silverado with TBI, so I know the system pretty well.  

Easy go to Summitracing and select your engine and model ant they have all of the manifolds that would work.

The TBI would be the way to go unless you are going to make too much power for it.

The Holly 750 would be much too big for a mild 350, you could use a 600CFM up to 400hp.

That being said the manifold and carb are not what you need, so sell them then rebuild around the TBI use. You can sell the TBI motor, ECU, manifold and carb and put the money towards a built 350 with a carb if that is what you want.