See now that's where putting a torque capacity rating on a transmission is just a marketing tool. You could put a 23 spline box behind a 1000 HP HEMI with 800 FT.LBS. of torque as long as you put a slipper clutch in between them If you put that Mcleod box in a 3600 pound B-body with a 14" slick and a Mcleod Street-Twin it will fail If they rated a transmission for "intended usage" you would see a much different price tag on them. They should include the proper clutch package with a transmission for the weight of the car and the power of the engine
I never hurt an 18 spline HEMI box until I put a Mcleod dual disc clutch in the car that didn't slip.Then I started breaking stuff and I might be pushing 600 ft. of torque

The shifter position is still gonna require extensive mods to the torsion bar crossmember

Gus