I haven't used that Alclad colour yet, but I painted my 3P0 with a base coat of silver chrome with Tamiya clear yellow on top (Same for my Batman Type A utility belt). It gives a nice yeloow-gold look, and then for 3P0 I weathered him extensively.
I used the Art of Star Wars book as my reference for 3PO. For most of the movie, he had serious wear and tear, and on one lower leg the gold is mostly gone, showing the steel/dark aluminum underneath (The leg may have been a replacement part from another droid). For this reason, I painted him silver with clear yellow over top, so that I could control the 'density' of the gold colour (I think I used Tamiya Gold Leaf, too, to darken the colour). I heavily weathered the silver, though, so it's very dirty and dark.
Troy, I haven't checked the net yet, just started looking over pics a couple of weeks ago in between other stuff. Figured I wasn't ready to commit to starting yet. But check out your library for some of those oversized Star Wars books like the "Visual Dictionaries" and others, there are a few very large and clear shots to be had of both droids. Unfortunately, usually just one whole-body shot each of the front, no close-up details of Threepio's fingers or anything like that, but still good overall. Threepio's uneven plating really shows up in the "Star Wars Visual Dictionary" covering the OT.
The Kaiyodo kits were 1/6 scale; just from memory, I'm guessing that the MPC kits were almost the same, maybe 1/7 or 1/8 (I think their R2 was better in overall proportions than 3PO, who looked a little 'stumpy' to me).