Information on the 273

The idea they like to rev is cause of air flow they have a similar head flow to cid ratio as a 340, obviously less hp potential then a 340 cause of overall head flow and rpm needed.

Basically the difference between a 2bbl 318 and 273 is bore size 3.91 vs 3.625 and rest is fairly identical for all practical purpose why people general group them together 273/318 and 360/340 cause each group has there own heads and engine mount. Sometimes there group by crank stroke so 273/318/340 with 3.31 and 360 with it's 3.58 and larger main bearing. I group by bore size 273/3.625 small and 318/360/340 3.91/4/4.04 same ballpark. A 4 inch bore is just over halfway (3.98) between 273 and 400 bore of 3.625 vs 4.34.

Other than bore size, early years having a different intake bolt angle, closed chamber heads and solid cam, other then that and being mopar 1st LA engine and 1st high performance LA with 235hp there's not too much more to say about them.