well, the world of Angell in the protectorate is a site of Irian Technologies, so i'd look at what they make there to start. while the onlything we know that site makes is the Juliano, we can presume the Cats could work a deal to license one of the other designs to be made there as well.
this would mean the Hermes, Hermes II, Trebuchet, Guillotine, Tempest, Awesome, Albatross, Wasp, quickdraw, blackjack-O, strider, and Stalker could be possibilities.
the Blackjack and Strider Omni's could be refit easily, just mount clan weapons pods. (and even if not being built specially for the protectorate, likely would be something they purchase.)
personally i'd pick an older design (easier to license and build), and give it the "C" refit treatment.
like say, the Hermes II -2S model, refit with a clan AC5, ERML, and flamer. say a UAC (and use the saved ton to add more ammo)
with a succession wars level chassis, engine, armor, and single heatsinks, the basic design would be cheap to build. and the clan weapons mean it can boast firepower on par with the post-Helm -5S model, without resorting to the use of Endo and DHS of that model. not exactly spectacular, but a goodway to bulk out the touman on the cheap side.
or the trebuchet -5J model, using clan LRM's to bring it back to the dual 15 rack, drop one ML for extra ammo, and upgrade the remainign 2 to clan ER's. no major heat issues even when jumping, your firepower stays pretty much the same as the non-jumping introtech model, and you now have better endurance.