I did a similar thing for the u bolts on my 68 chevy c10. I couldn't afford to purchase a 3/4 torque wrench for 4 nuts. welded up something similar, but it was only 24" long.
for the carbon you can use lye. I frequent a coleman lantern restoration forum and people often use a lye or a citric acid solution to get the years of carbon deposits off of the brass burner parts.
I was just thinking i should give mine a cleaning. How exactly did you get the ring off? I was just going to try prying it off. Mine is a newer double pawl one that says oil only so i may just put some 3 in 1 in there.