I've done a ton of research- so now I'm really confused....

JBurch said

As already the heads on your 273 are small closed chamber; there would be no real benefit compression wise, to go to 302's other than hardened exhaust valve seats. You would have to grind away a portion of the head; smog port bump; on the drivers side to make your exhaust manifold fit/lay flat on the head. Cam shaft change........try a stock 360 hydraulic, by the numbers it's slightly bigger; more duration, equal lift; than the 235 hp cam

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I've read - as my post said waaaayyyyy too much research - that these heads have small valves - 1.78 /1.50 which is the same as the original heads valve sizes - but have an aggressively small "Fast Burn" chamber that runs around 10cc smaller than the original stock heads - which is my "cheat" to get a higher compression ration without pulling the motor itself with the bonus of hardened exhaust valve seats so no worries about gas....but I could be totally wrong which is my concern.