Carburator switch

[guardianfyre]

Got a question for everyone who has more knowledge of engine components than I do (which probably includes everyone on this forum...). I have a '79 Chevy 1/2 ton. The motor is not the original (original was 305, current is 350) but the carburator is. I'd like to find out how difficult it would be to switch from the 2 barrel (?) to a 4 barrel (?) and if anyone knows if there is a throttlebody system available for my year of truck. How would changing to a larger carburator affect my gas mileage? Is there anything else I should know? Please consider me a complete n00b when it comes to working on vehicles. The most I can do is check and add fluids and give my truck a tune-up (filter changes, oil change, radiator flush, spark plug change, etc.). I'm willing to learn, please teach me.

If you need more information than I've given, please ask. I'll do my best to answer any questions.

~Fyre