I believe a TF727 with that amount of clutch plates and proper line pressure should hold up to that torque with no problem. Likely an issue somewhere else, seals, etc.

7/5 clutches and 160 psi will holds tons of torque, IMO.

I don't have that much (time and weight in sig), but I have 5/4 at 165 psi and they are lasting for many years. I think this is my 5th on the same parts and I have inspected a couple times.

1993 Daytona, 5.50 at 130mph (1/8) 1.19 sixty ft (PG). Link to 572 B1 - Part 1