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

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