Hi Stephen
Yes, I've got the cap, it looks to be good quality. I made a filler neck and have welded that in.
I start the metal finishing by hand sanding with 100 grit and work up to 400 grit.
After Wheeling but before sanding the metal looks and feels very smooth. As soon as the sandpaper hits the surface hundreds of tiny Wheeling ridges show up. It took a few hours of hand sanding to remove all of that.
Next I start in with buffing wheels on an electric hand held polisher.
I have a special type of non wax based buffing compound that must be kept stored in a deep freeze. It starts at 100 grit and goes up to 300 grit. Unlike the wax based stuff, this stuff really cuts!
The 100 grit removes all of the sanding scratches, but it's necessary to slowly work up to the 300 grit in order to obtain a nice finished polish.
After the 300 grit compound I switch to conventional wax based compounds , medium, then fine then finish with jewelers rouge. All done with hand held electric polisher. I find that stationary buffing setups tend to grab the work and fling it across the room!
This tendency is a bit less somehow with the handheld.
Maybe it's easier to see the angle of attack and avoid using the wrong one?
Glen