Edelbrock Heads for 318
Magnum heads can run the old LA valve covers, but it may take a little finagling to get them sealed permanently. You need to have the Magnum heads re-drilled for a std LA intake bolt pattern. But any shop can do that very easily. You will have to run the Magnum rockers, and AMC lifters and pushrods because the rockers oil thru the pushrods on MAgnums, and thru a shaft on LAs. The Magnums have the smallest chambers..IIRC 53cc, and the best factory ports, plus decent valve sizes. That's the heads to use IMO.