I have a 1970 Mopar 318 LA that the previous owner put in my '56 Dodge, I'm trying to make it a decent performance motor on a budget, well as much as you could make a 318 powerful of course. But my question is, I've already planned on buying a Holley 600 CFM 4bbl carb, beefier cam, and a MidRise intake manifold. With the bump up from a 2bbl to 4, I read up that to compensate for the change either any 340 heads, 360 heads (with 1.88 Valves to flow better with the 8.6 compression that the 318 has) or mid 80's 318 (302 casting) Heads would work. Between all 3, the 318 heads seem the most economical choice, and wouldn't have to buy new pistons (to compensate for the loss of compression), but I'm not too bothered over spending a couple more bucks if the other options would give better performance. I'm worried the 340 or 360 heads would lower compression too much and dog it down, but with any choice, portwork would be done. Any help would be useful, would love to hear your thoughts.