273 Commando Top End Rebuild on my 65 Dart GT

Are you sure that's a real Commando? Those don't look like the domed, hi-comp pistons to me.

If there is a ridge at the top of the cylinders, that denotes a fair amount of mileage on the engine, not a low-miler.

...and, to nit-pick, the cylinders are numbered 1-3-5-7 on the drivers side and 2-4-6-8 on the passenger side. If cylinders 7 and 8 are low, then that would be the 2 rear cylinders, one on each bank.