Newbie Here....66 C20 A Few Questions

[NWSooner]

Greetings friends!

I'm a TRi-5 Chevy guy by nature but have always loved the 60's Chevy Trucks and when I found this one ROTTING away in the Pacific Northwest I had to rescue it!

1. The guy I bought it from told me it had the 250 in it, but I'm not confident he has much of a clue....How can I be positive which Inline 6 I have?

2. I've changed points, plugs, cap, wires, coil, adjusted valves and carburetor. It sounds OK but takes like a minute or longer for all of the fuel to burn up and idle down. Looks like the stock Rochester 1 barrel, would a rebuild kit be worth it or should I opt for a new carb all together or could it be another problem?

3. Needs a new muffler, any suggestions on what might add a nice little rumble to this old girl? Look I know it's a 6 banger but still I honestly think it had the original muffler on it, truck only has 54,000 original miles on it.

Thank you in advance!

NWSooner