Great find Brian!
I polished ours
on Maxwell...shortly, I'll be doing another pair for Birdy. It is a PITA! But looks great great when done.
I too lightly sanded some of the casting imperfections with fine sand paper, using whatever tools I could to get into all the nooks & crannies. A lot of the top around the handles & valves had to be done by hand...even my Dremmel tool was awkward. I used the compounder & Cyclo on the body with the different Nuvite grades (because we had it from trailer polishing) but so much had to be done by hand, it didn't really matter. By hand, I used "Nevr-Dull Wadding Polish
" and it work very well on the tight spaces. You can get it at Wal-Mart or any Auto Zone-type store. No matter what, it's a dirty job...give you a flavor of what we vintage folks go through on a whole trailer!
Depending on your climate, they will probably look good for 5 years or so before you have to re-do them...it you keep up with the oxidation annually, a half a saturday a year should be good. I wouldn't clear coat them...it gets nicked & scratched everytime you go to fill the tanks, then you'd have to remove it before polishing the next time.