I'm still a little confused about some things converting TBI to carb.
Do I need a different fuel pump. I was told that some carborators would regulate fuel. I really hope thats the case because it would make my job easier. If thats true, that will the Holly 750 or 850 do that?

Also this is going on a 305 bored .030, 350 heads. Which carb should I go for 750 or 850. (can get a really good price on them)

 

The TBI pump works at 12-15 psi as I remember. When I converted mine, I changed the whole fuel system (cell, pump, filter, braided lines, etc), but at minimum, you will need some type of return style regulator or a different pump that is rated to work for carb use. 12 psi will force fuel past the needle and seat of most carbs causing it to overfill the fuel bowls and making it difficult of impossible to tune. So, I doubt that you'll get away with "just sticking a carb on it".

My thoughts.

On a 305, a 600 cfm (or 650, whatever the carb comes in) is usually enough. Many street 350's don't need a 750, and a 305 will be very unlikley to need it either. If you insist on a 750, make sure to buy a vacuum secondary carb, it will be much easier to tune and run far better than a mechanical secondary carb that is too large.

Have fun!

 

trackbird is dead on about the carb, but I'd just like to add one thing. About the 350 heads on the 305. You either need to mill the heads siginificantly or change the pistons. Going from a 58cc 305 head to a 64cc or even worse, a 76cc 350 will absolutley KILL your horsepower. Compression ratio will drop significantly, and the engine will perform like a slug. Oh, and one more thing. Stick with 1.94/1.50 valves MAX. Anything larger and you'll have serious problems.