got the advice from the kind people here on how to polish them - but then went ahead and used mostly what was lying around to do it.
my own method began rather badly - i used some harsh metal grinder discthat I later needed to correct (lots of deep scratches) with much other rubbing. on the second cover, I used a much softer grinder disc and followed it up with those foam sanding pads (fine grit). These worked well. I then went to work with rubbing compound (also used the foam pads to rub in the compound), followed by Mother's Aluminum & Mag Polish, followed by wet sanding (1200 grit?). Mine are not shining like chrome but they look SOOO much better than they did. I plan to take off the valve covers this summer and have a go at those to get them to shine like some people here have done. It's kind of scary thinking that my bike might really shine, maybe too ostentatious. I'll get confused for a Harley rider!
lacquer may be forgiving and polish well, but it will NOT stand the test of time and lots of things will ruin it (besides the weather), as above, two part urethanes are the best but WEAR A RESPIRATOR that stuff can set up in your lungs
I don't know that I would ever mess with clear coat once I got them buffed up good. When I bought my 83 1100 I used paint gelstripper and stripped them bare then mothers about once every 2,000 ,miles or so for the first 100,000 then I went to extreme wadding with a sealing polish that came with it this dropped my frequency down to oil changes when. They looked better than chrome IMHO because the shine had depth. I'd like to see a set of covers that were highly polished the had urethene applied but until I see them this old horse is stayin in the field he knows.