I forgot to add to the above post that a buddy of mine ran a very hot 350 engine with a B&M blower driving a TH350 in a 40 passenger school bus converted to a motor home for years. He had no problems with the transmission, and I can guarantee you, that as a retired top fuel driver, he beat the crap out of it. Synthetic transmission fluid and plenty of cooling helped keep it working right.
Bob


55 Cameo 396 TH 400 with overdrive
65 Caliente conv
67 BB Caliente conv
67 Mercury 1 Ton
76 GMC 3/4 ton 454ci
84 Buick Turbo Regal