Conan's got a gazillion. Cormac Mac Art got quite a few back in the '70s, for some reason. Heck, even Bran Mac Morn got a couple and Black Vulmea. But Kull? Outside of comics and a few fragments finished by Lin Carter --- nothing. So why is that? Does Kull's brooding, cerebral nature make him less appealing? Or is it the fact that much of his time is spent as king, in and around one kingdom interacting with the same characters too limiting? Is there any chance that we'll ever see original tales of Kull as king, or even before? But even Marvel didn't do much with the young, pre-king Kull, and they did more with him than anyone else. I would think there's some room in his younger years when he was an outlaw, gladiator and mercenary. I know that, given the chance, I'd love to do a Kull pastiche rather than a Conan one, if only for the challenge.
That is true. Arvid Nelson had problems (I didn't mind Igraine but I understand why more purist fans disliked her) but I respect he made a few attempts to spice it up (his first issue had Kull putting down a nobleman who was rebelling).
I will have to hunt down "Treason in Zagadar" now.
I suppose that Kull pastiches in the past have been too limited. Most of Marvel's revolve around some threat to Kull's kingship, meaning that after a while, all the stories seem the same. Even Moench's stories --- which are very good --- are also a bit like Kull's Greatest Hits. They don't break much new ground. That's probably because Kull is best known for being a king. A pre-kingship story would have to take care to not come off as a generic Sword and Sorcery tale.
You could try the novelization of Kull the Conqueror by Sean A Moore. I have not read it, but fans say it's a lot better than the movie, which is not really saying much. In my experience, all of the novelizations of the Conan films were superior to the films that birthed them...
Roy did quite good work with young Kull back in his days. Since Exile of Atlantis he takes Kull into Lemurian slavery, then go on his gladiator days, even there is episode in wich Atlantean meets for the first time a wolf man in the arena. Long is the time since I read it, but, as I recal, in those days Roy introduce ol' Rotath in saga. It wass a good work if not the best. I have to search that serial again.