Confused newbee with a 273

All of the die/blow hards are gonna harass you for calling a Barracuda a Cuda.

Main things with the small block heads are port size, valve size and closed or open chambers.

Not a lot you can do with a 273's small bores without a lot of work. I'd say plan for the engine you want, 318 or 360. That will dictate your cam, heads, etc.