There are salvage yards that can order in parts, that is my main advice here. Got a 1990 t-5 in 1991 shipped in on a palate, was awesome. Got a beat up 85 t-5 a few years later from individual, had the wore out shifting feel. Got a 99'ls1 with 6 speed, 33k miles in 02' from a guy traveling car shows selling late model take out stuff, he's retired now. 6 speed is great with the .5 ratio 6th gear, with 3.73's & 29" tires, about like your gear & tires, it doesn't hit 2000 rpm till 92 mph. clutch pedals & mc mount made up as there were no kits then & not perfect especially pushing my stage 3 monster clutch. I think mcss, sick speed??, has the best pedal & mc kit .
Another option highly likely may be to buy the whole car with trans & part out. Parts worth more than whole car.
BUT, here's my thoughts for your situation. 6 speeds are highly wanted , expensive, & hard to come by, plus cost of correct flywheel, clutch, bearing, pedals, m.c. , line, slave, modded or new crossmember, speedo hookup, shorter shaft. For later down the road going new as possible ( ls3) complete with matching trans & wiring may be a good thought. For now, costwise, settling for a good built slushbox, hookup parts, modded or new crossmember, & shorter shaft would 9 out of times be cheaper. Could reuse shaft & crossmember. Just as easy to sell od slushbox later.
New magnum would be awesome with all new parts, but everything complete could push towards 5k cost. unless you had the perfect engine, this would go a long ways towards a complete ls3 setup, with a tr6060, which is internally a magnum.
But I'm not in a position to talk anyone out of a stick shift. You just need a different search to find a worn out remaining LT1 version. Likely won't shift like butter, but you will have your gears.