After decades in this brand/hobby, I think they look best painted red; but that's an opinion. If you want it to look as pure as wind driven snow, clear will never do. Paint it with aluminum colored paint.
its not a very rugged casting. i wouldn't hit it with anything more abrasive then glass bead. the oil and grease will clean up quick with the normal methods.
aluminium acid etch type cleaner did wonders on my b4b. It will bring it back to white with repeated applications. Degrease the cover as well as you can first for best results. Not sure about "safest" since it involves acid. I followed the directions and neither my b4b or myself suffered any damage.
Oven cleaner followed by psi washer, then brake cleaner for the rest, run brushes up the oil ports , brass brush for stubborn areas ,clean any casting flash out then paint or whatever If you have access to bead blaster then after its degreased blast it then a good bath in psi washer and degreaser ,parts washer or brake cleaner
Good idea to chase all the threads as well and block sand the oil pump cover, and sealing surfaces with 180grit
Use tons of B12 chemtool until you see stars, then call the hospital.... Just kidding. If the cover is still on the engine, the safest way is to blast it with a steam cleaner. Use non-petro solvents to loosen caked dirt, then hit it with the steam.
