My general recommendation if your sizing is super specific and hard to find OTR, go made to measure: Luxire, Proper Cloth, Spier, Suitsupply, Enzo, etc. Measure pants that fit you best and go off of that. They'll usually do a remake as well if it's off a bit.
I think the only B&T I've actually utilized is Levi's
For ready to wear items, Look around for some pants that have unfinished hems. Jack Donnelly chinos come to mind with a 39” raw inseam. Some wool trouser brands come unhemmed. Levis sells some 36” inseam (at least for 501). Dickies 874 has some 36” inseam for certain waist sizes. Some of the Japanese denim brands come with 35-36” Factory inseams