I think that Kull digest from Thomas and Smith was intended to be published outside the mainstream. Also there's Jaxon's Testicles the Tautologist in Slow Death where Frazetta Conan meets Smith Conan. Fujitake must've done some Conan art for Amra or other Howard zine somewhere.
Jaxons Conans are interest'n (never saw it til now, somehow) and I've long grooved on the Kull stuff by Smith, but what I'm most intrigued by is your comment that Fujitake should be in Amra and such. This has caused an eruption in my consciousness (#mindblown) and I am now on the prowl