It's rated for 700hp/700lb-ft. It uses a 26 spline, longer input shaft, so you will need a different bellhousing than the typical Ford T-56. It also has the same shifter configuration as the TKO 500/600, where the shifter can be relocated to different positions to fit the vehicle.
Michael,
I steer customers away from the T-56. Unless you're running a 4.88 rear gear, I see no advantage to having the extra bulk of the T-56. In several of the replicas, the T-56 won't physically fit without a lot of work.
You would still get 600 lb-ft of torque from a TKO 600. It's going to be about $800-900 cheaper than the Magnum T-56, and it will be a lighter/smaller box.
Depending on what clutch you're using now, to swap over from a Toploader to a TKO would require a different clutch kit, clutch fork, and a TKO with a short input shaft conversion.
To swap over to a Magnum T-56, you would need a different clutch, different bellhousing, and a different clutch fork/pivot.