If you want to clean it up, why not paint it? Chrysler used an orange for most of their engines (even had an official "Hemi Orange" for a few years,) and most companies have a "Royal Blue" that is fairly close to what AMC used on their engines. If it's 1991-up, use Chrysler orange, and 1990 & earler can use AMC blue (that's the production split anyhow - even though ChryCo bought AMC in late 1987 or early 1988, the Chrysler specs didn't show up in production until MY1991.)
Painted metal still rejects heat rather more efficiently than chromed metal, so you won't be running into the heat problem.
Also - and take this from a guy who has built a few "chromed" engines - you won't be happy with the look or the results unless you are absolutely anal about assembly. When building or installing a chrome-dressed engine, I usually go through an entire box of gloves - and still spend an hour or two wiping off fingerprints...