Best 318 heads

If you want to compare apples to apples, some of which are actually orange, think about the "old school" series of bored 283's to 302, and the late 60's 327, and 68/9 302 Z28

"Just how good" were those old heads? Most of the late 60's HP 327's were NOT 2.02 valves, they were mostly 1.94s

There's no reason you can't duplicate that with a good set of LA heads. Anyway you want to play it, magnum heads are an EXPENSIVE swap, and when you're done, none of your "old stuff" will fit your "new stuff" including cam and lifters, and intake, or rocker gear