I hand sanded with 400 and 800 grit to get rid of the paint flakes the stripper didn't remove, followed with metal polishing wheels on a handheld drill, a kit a bit similar to this but smaller diameter wheels:
I bypassed the first coarse disc that is meant to remove material so you get a perfectly smooth surface that will mirror polish and went straight to a stitched cotton disc on a drill with blue compound and finished off with a loose cotton disc and jeweler's rouge. To get to the nooks and crannies I used similar small pads on a dremel. This particular case was quite easy to do, I've been told the older 8274 castings were of higher quality, so that may have been a factor.
If you really want to get a mirror shine, using a coarse sisal disc with heavier grit compound to start should get the job done quite quickly, I just didn't see the point since aluminium tends to oxidize quite quickly, my goal was to achieve a smooth finish that's easy to wipe down and won't be subject to fast, heavy oxidation and pitting (the typical white powder residue that tends to appear quite quickly on rougher castings).
I have a bench polisher as well, but didn't bother with it since the larger diameter of the discs is poorly suited to get into all the nooks and crannies of the 8274 casings. I did put the parts in my 20L ultrasonic cleaner afterwards to get rid of remaining polish stuck in the rougher parts of the casting, but some solvent and a bit of patience should work just as well.
You should be able to achieve this over a weekend working at a leisurely pace, but I wouldn't bother unless you're stripping your winch down anyway, manhandling an assembled case with brake and drum attached would probably be a pain if you were really intent on polishing the entire thing and not just the top housing.
I didn't intend to even go this far, but due to Brexit, I ordered a bunch of toys from Gigglepin 4X4 in the UK when it was still "cheap", I will be building it up with a 24V 7HP Bowmotor 2, some reinforced top housing bearings and brake linings and an Albright solenoid. A bit overkill for my purposes, but still cheaper than Warn parts over here in Europe.
