ID 273 Commando that's apart

Assuming this is a 66 or older motor - the major differences will be the cam, the pistons, valve covers, distributor and the intake. As far as IDing them the cam is pretty difficult to tell without a dial indicator set up to measure the duration. The pistons again are going to be tough to figure out, they will have a taller compression height than the 2bbl version, you need the specs for the pistons to determine whether they are 2 bbl or 4 bbl versions. The valve covers and intake will be obvious. If you can, try to get all the kickdown and throttle linkage parts, these are really hard to find in a complete set. The rest of these 2bbl and 4 bbl motors are the same, rods, crank, heads etc.