I was wondering what you would have to do to convert a fuel injected 305 to carburated.

 

A lot of stuff. You have to regulate the fuel pressure down, get a non-computer distributor, carb intake, carb, air cleaner, and basically rewire the entire engine compartment. If the car has an electronic speedo that won't work anymore because it runs through the EFI computer. You have to set up a manual torque convertor lockup if it's an automatic. You have to fabricate throttle/kickdown cable brackets. Your cruise control won't work.

I know all this because I have done it.

The advantages are: if you're taking out TBI then you'll gain some power, it'll clean up the engine bay and make it much easier to work on, and engine mods will suddenly seem very very cheap by comparison. Go ahead and change the cam since you have the intake off anyway, and it might be worth it.