Well, jetting has to do with air/fuel mixture. If you decrease jets you dont stop the airflow, you limit the fuel. This means you are running lean and that makes for a hot and destroyed engine. You can try to cam it up a bit, but I am not really understanding why you have the desire to put a tunnel ram and dual carbs on a stock engine? Your doing an exotic induction system on a turd? Get a set of good heads, a nice hydraulic roller cam, make a 355 or bigger and actually use that induction system. Otherwise all I can see you doing is making a huge mistake just to make it look like a it may be a performance engine. Sounds a bit like a not well thought out plan. Sorry man, its just my opinion.