Wow, thank you for all your comments. When I write up my (very casual) investigation I'll post it here.
I did not finish the bow very carefully but found that after sanding with 120 grit, it self-polishes by rubbing with sweaty hands...hot as hell here... It is also much heavier than Elm or Hackberry - the other woods I've made bows from. And I do think it needs to cure longer. The dense heartwood does not dry easily. I did leave the ends a little thick and heated a slight recurve in the tips. Seems to take a bend easily. I'm currently trying to straighten and strengthen another Huisache flat bow I made earlier that is only ~30# but 70" long. I'm sure the natives used heat to modify wood tools of all types. Tom