Mmmmmm.... we have some heads (675 castings) off of a '68 273 and a number of the exhaust valves are recessed into the heads pretty badly. It is easy to tell. I would not do the early V8 heads without seats, only a /6 with their weak springs.
The Commando 4 bbl pistons should be easy to tell; they have 2 eyebrows on them, have a dome, and come in left and right sets. The 2 bbl pistons have 4 eyebrows on them so they can be used left or right.
The VHT Engine Enamel Chrylser Red is a super good match to the original color. I matched it on an original paint /6 distributor splash shield and you could never tell the difference. It is at Oreally? and Madvance; not sure about OtterZone.