I was going to post my opinion on this but it looks like you found out the right thing to do... usually once the plating starts to peel there's no saving them because it's almost always separated far past where it's missing. Some times you can save them, but in most cases you can't. Glad to see you experimented on the old cylinder, there's always a small chance you can save one, but they do make interesting paper weights and a good place to practice your porting skills so it's still worth keeping.
With the new cylinder, I've seen some that the plating actually overhangs into the ports so the new one may need a clean up at minimum before putting into service as these little overhangs will give the plating a starting place to separate. A light sanding chamfer is enough to prevent this by bringing the plating up even with the ports then chamfering around the outer edge.
That jug does look good, but I live in Texas where I'd be conearned with the heat not being able to escape past the thick paint efficiently enough. But black is good when you want max heat transfer since it'll absorb the heat. A thin coat of matte black on the jug & head, and wrinkle finish everything else would look really nice and run nice and cool.