750 barrel colour & recommended paint

Early 750 Commandos barrels were silver until the combat when they were black though I believe there were early bikes with black barrels. Quoting from Roy Bacon's book, "The 750 Commando block was launched in silver paint,changed to black for the early production and became silver again in march 69. For 1971 it was strengthened and for 72 changed to black for the combat engines. The silver was retained for the standard engines and continued on the 73 engines which kept the same block"

I've had mine powder coated silver but I woundn't recommend it, seems to stain and is soft when hot compared with my previous black powder coating.

For the base I greased my gasket but if you have no faith in that, then welseal would be my weapon of choice.

My 71 Fastback was registered in 71 but club records show it was probably built in late 70

850 Mk 1 and Mk 1A also had siver barrels - changed to black for Mk 2A and Mk 3.

I use Halfrauds High temp silver on mine. It leaves a bit of a dry residue but is quite tough, though no comparison to stove enamelling. It does not discolour unlike the PJ1 used on the cases. See pic.

Re base gasket, you should have no problems with Andover Norton gaskets. Fitted dry is all that is req. assuming mating surfaces are flat and clean.

Barrels were probably painted silver to look like alloy, because AMC could not afford to use the real thing! Personally, I would have them blasted back to bare metal, then go for matt black, which radiates heat away better.