I've got a 15 (or 16) gallon drum, also. I had been planning on turning it into a mini UDS. Carbon, you might just have me convinced to go the same route as yourself, and either take the bottom off of the drum, or fill it w/ holes.
Did you simply load the SJ bottom with coals, or did you fab a small charcoal basket (ala the tamale pot mini wsm)? Excellent job on the leg mod, too. What size flat stock is that? And is it aluminum?
You've made yourself quite a nice cooker... looking GREAT!