When you get the vacuum leaks solved it needs at least a 700/750 Holly or a 700 demon. I would start with a 800 thermoquad, i like them and can tune them, that is what originally came on a 340.
But first you really need to find why it has a giant air leak.
I would also do a compression test to see how hot that motor is. Mine is a 10.5 to 1 and have compression around 200. It just gives an idea of how much squeeze your cylinders are giving. I need 93 and up to run. It is in Charger but B Body sites barley talk about small blocks.
View attachment 1715919983
