Best 318 heads
All 273 heads were closed until 68 right? Just the earlier ones had the funky intake bolts.
Anyway, I used the 920 273 heads from the original engine on my "new" 318. It's way better than with the stock 68+ 318 heads, but even with milling and thin gaskets I only get around 8.6-8.7 compression with stock flat tops. I used the guide at the top of the forum to do my own porting and installed an xe268 cam at the same time. Runs strong, for a baby engine.
Oh and the 920 are probably your best best on a milder engine. I think the 302 has a slightly larger chamber, and the heart shape won't do any good for quench on stock pistons anyway since you're not even close to zero on the deck. Plus most people (like me, when I first tore down the engine) will think the 273 heads are only good for the dump. EVERYBODY wants the 302 heads.