I've done a ton of research- so now I'm really confused....
The factory already figured out how to get more performance out of the 273 — domed pistons for higher compression, plus high lift cam and 4bbl intake. Big valves don't really help since you're limited by the small ports. Swapping heads hurts the compression, and what you want to do is raise it. There really is no substitute for the Commando-style pistons. So go for drivability as suggested, and save your money for an engine swap if that's your bag.