Spend another $1000 in porting to really make them work and the old junk will keep up with just about any aftermarket head. I have done X and J heads but prefer the "587" castings. I like to start with $20 castings from the junkyard. Much more satisfying than shelling out $$$$ for new heads. I've gone 9.02 at 149 at 2460lbs in the lebaron w 915 castings on a 449c.i. BBM and 9.68 at 136 at 3040lbs in the Demon with 587 castings on a 418 SBM. Neither car has a maximum effort engine. Both are flat top piston motors and less than .600 lift flat tappet cams. Either motor has about $1000 in parts and machine work in heads, and my porting which would equal about $1000. You would have to spend that much or more to equal that power level with eddys or the new RHS X heads. Anyway I like to see the guys make power with the old junk


418c.i. sm block mopar w/ported junkyard heads