Where's David McIntee when we need him? First Frontier creates a new Master, I believe, but I've never read it myself.
Indeed it does, though this Master only appears twice in the New Adventures, I believe.
There's a number of alternate Masters in the Eighth Doctor Adventures, none of whom are explicitly identified as such.
Time's Champion says that the War Chief was an early incarnation of the Master.
Though Craig Hinton was a friend, Time's Champion really doesn't count even within book 'canon/continuity/call it anything so long as we don't start off an argument about whether it counts in the series!'.
He hadn't finished it when he died, and nice though it is to have it available, it's not been published by the licenced publisher (ie, BBC/Ebury at that point, and earlier Virgin). It's like Jim Mortimore's Campaign, or the script book of The Masters of Luxor - a glimpse of something that might have been.
Also, Terrance Dicks' novels for Virgin (Exodus, initially) make it clear that the War Chief and the Master can't be the same person.
David McIntee's 'Basil Rathbone' Master appears only in First Frontier and Happy Endings, both Virgin books.
The Master who appears in the 8th Doctor comic strips is in-between the Eric Roberts incarnation and the Time Lords resurrecting him, in that he's again living on borrowed time in a stolen body (a dark-skinned street preacher/prophet of doom).
On trying to number the Master's incarnations... it's wild goose chase. There's no way of knowing whether the Deadly Assassin Master is the Delgado incarnation, unable to regenerate after a horrific maiming, or the result of a failed regeneration. Then the implication of the final shot of Assassin is that the Master is regenerating (that was the intention of the producer at the time), but it's not entirely successful (hence his slightly improved but still unhappy state in Keeper of Traken).
And then... David McIntee's Dark Path ends with the Delgado incarnation, before his TV debut, caught in a temporal trap which is forcing him to regenerate continuously without changing form as he tries to escape.
Add it all together, and all you can rally do is put them in order, no more. 1st known Master, etc, but don't try to connect them to the 12 regen cycle.