Well the MiG-29K’s primary armament is the R-77. It’d be better than the SMT, deserving of 13.7 in ARB. Even without R-77 it’s got an additional pair of hardpoints that can carry R-27s as well as a much improved radar, RWR, MAWS, and much more powerful engines compared to first-generation MiG-29s.
As for ~13.0 Soviet premiums there’s quite a few options-
Su-27P: Su-27S but without bombs. Pretty bland but simple and effective.
Su-27K: Prototype designation for the Su-33. I wish the Su-33 was TT and this was the squadron. It’s mostly here for reference.
Su-27IB: the prototype of the Su-34. Unsure what sort of armament it could carry; it’s so late it’s early and I don’t want to do any deeper digging.
Su-27: pre-production batch with AL-31s instead of AL-31Fs. No idea on the performance difference. Since the Su-27S is designated just Su-27 im-game (to be fair this was historically used as well) might be a bit confusing.

Su-27UB: twin-seat combat-capable trainer. Unlike the MiG-29UB it still has its radar fitted so it can still use SARH missiles and whatnot. The Su-30 (AKA Su-27PU, the Su-30SM we have in-game is a much later model) was basically an Su-27UB with upgraded radar.
MiG-29S/SD/SE: Upgraded MiG-29 and two export versions, all pretty much the same as a basic MiG-29 but with access to a pair of R-77 on the R-27 pylons (and R-27E, R-73 which ofc weren’t specific to these models). Probably 13.3 unless Gaijin just doesn’t give them R-77 which wouldn’t be too unreasonable IMO.
MiG-21-93: What would become the UPG, with avionics upgrades and access to R-73, R-27, and R-77 (which the Bison should also have)
MiG-23-98: My personal pick, a MiG-23ML with R-73, R-27, and R-77 plus an enormous avionics upgrade to roughly MiG-29SMT level
MiG-31BS: MiG-31 Izdeliye 01 brought up to MiG-31B standard (we’d of course need the 01/01DZ and 31B first or at least at the same time)
And for a “direct MiG-29G equivalent” there’s also the 9.12 which would be pretty much identical (so a bit less interesting IMO than most of the options above)