Heads leak bad on 86, thank you for mentioning heads can interchange, 340 crank was for future build with 86 and maybe sometime aluminum heads, and said rockers. 86 has speedpro hyper .030 over pistons, isky 270 hyd cam. 72 was for noatalgia type drivetrain. Saves me time for what to take with me to spring fling trades. Would love to have one 318 and the original slant it came with.... Seams it is better to keep 86 short block for when Blue 72 gives up.