X-Men #26 and Uncanny #307 are both collected in Bloodties, so that's those already taken care of.
A Phalanx Covenant OHC could include Uncanny #312 to 319 and X-Men #36 - 39, with Uncanny #306 included for good measure and minus Uncanny#315, already in Fatal Attractions. And while we're playing Fantasy OHC, it would also include the crossover issues of X-Force, Excalibur, X-Factor, Cable and Wolverine, as well as the first 4 issues of Generation X.
So that would leave X-Men #17 - 24, Uncanny #308 - 311, and X-Men #27 - 35. And that's not including any relevant Annuals or issues of X-Men Unlimited I've forgotten. Is there any common thread in those issues? From memory, the main stories are the wedding of Scott & Jean and the whole Revanche/Psylocke thing. There are other stories as well, but i think those are the main ones. Would those or the other stories be marketable enough to sell an OHC?