A couple of things.

The TKO 500 and TKO 600 are rated at 500 ft/lbs and 600 ft/lbs respectively. Rating them in horsepower seems to be a marketing ploy.

Also, unless somebody can enlighten me, not one car ever had a TKO series transmission ever installed from the factory. Tremec does make OE trannies like the T-5 and T-56 but the TKO trannies are purely aftermarket transmissions.

I installed a TKO 600 behind a 440 cuda and ran 11's. It shifted wonderfully. Reliable as heck. However, I did my own hackjob using the tried and true Mopar clutch linkage and used Tremecs in-line short shifter and cut a hole instead of an outrigger design which I can't imagine helps gear changes. Obviously since the OP wanted just a bolt in setup he couldn't have done the same as me.