The T-45 gears are fairly stout and extra strength can be achieved with a custom 26 spline input and cryogen tempering of the gears, but I wouldn't say it can be built that strong. If using street tires and a conservative clutch it may hold.
The TR3650 gears are actually stronger than the T-45. One with the above upgrades would conservatively support 600 ft/lbs of torque.
There is a custom TR3650 gear set rated at 700 ft/lbs.
1965 5.0 Coupe /MAF/EFI/Astro A-5 T-5/B303 Roller Cam
Mustang Manual Transmission Specialist