340 heads on a 318?

318's run very well with 340/360 heads, intake valve size is not important. Magneflux any used heads to make sure they are not cracked first. Always mill them .020 on block side and .019 in intake side if they haven't been milled before. This gives you a flat surface to seal to the block and keeps about the same compression ratio. Clean up the bowls under the valve, see Wild and Crazy's thread on porting heads. Tighten the guides and get a Good 3 angle valve job. This is a cheap way to add horsepower to any 318. The ported 318 heads are no longer available from Mopar Performance and cost a lot of money. If you trust your porter, and the money is in your budget go for it. The "302" castings are the ones to use. Air flow makes more power than compression... Do you really think 22 cubic inches makes that much difference that 340 /360 heads won't work on a 318????