KBT Pure and Poker X have PS/2 protocol also, but they're hard to find nowadays since they're not made any more.
May I ask why Costar stabs? If it's just about the "mushy" bottom out feel of Cherry stabs, you can clip them and then they feel as good if not better than Costar. Plus they're less fiddly when replacing caps.
If you MUST have Costar stabs, for TKL you have a few choices, Filco MJ2, CMStorm QFR, etc.
For 60%... not so much. There's only the MiniLa. But it has a very odd layout and not so good keycaps, which means you can't replace them and are stuck with the stock thin ABS caps.
If you want to go 60%, don't worry about the stabiliser type, just clip the Cherry ones and enjoy. Ditto for the PS/2 support, unless you have a very specific reason for needing it.