Old School vs Magnum on 86 Dodge W100

You might want to ask about the cracks in detail from the shop, and then inquire here. How deep and long and numerous are the cracks?

If those are 302 heads, then that is supposedly common.... Some guys here will refuse to touch them, and some guys here will run them all day with the cracks. I don't know enough about the 302 crack situation to be of much help, except what I have just reported.

Those Magnum heads have smaller combustion chambers, nominally 62 cc versus 68 cc's for the LA318 heads. So the compression is better for low RPM torque, which is an attribute to pursue for a street truck IMHO. The chronic issue with smog-era 318's was low compression ratio and it takes pistons like KB167's to really correct that.

Are you planning to cam up this engine at all?

BTW, I would expect more wear in the LA318 block, but you gotta measure to be sure. The Magnum block is .015" shorter so has a bout .25 point better compression from that alone. Seems like the block is OK...yes?