273 commando. How 2 tell?

it has an aftermarket alum intake? depending on what you're doing with it proper intakes can be a bit difficult to find but not impossible. The Covers and air cleaner and proper # carb are nice. Dual point dizzy's were generally tossed away years ago.
Hard to find a 45+ YO engine without being rebuilt at least once. So even with that said if it is an untouched commando engine - pistons, if once done the pistons may not tell you. You will need to measure piston height in bore etc and calculate compression ratio.
The nice thing is oversize commando pistons can now be obtained through egge. So you can make a 273 a "commando" if it has the wrong pistons. There are no other discerning marks to tell one from the other, maybe cast/steel crankshaft. Mostly bolt on goodies and pistons.