383 with Eddy heads!
all you have to do to a set of 516 is over-size the exhaust valves. I did a 383 with 516 heads and only put 1.74 exhaust valves out of a 906 head. that motor won me many dollars and trophys in my mud bogger. 440 would not touch me. the 440 is a turd motor unless you lighten up the rotating assembly. The pistons are just heavy because of a 2 inch comp. height. plus the stock 383 has the best rod ratio of any production motor 1.86:1 (on memory not sure) formula is: rod length/stroke. and 383 is lighter.