Your TL I reckon is a normal 28 spline output & small first motion shaft box, I can probably build it to be a Bull nose with new parts which is what was used in cars with greater than a 390 FE car fitted from new, you can also run better bearings than stock. As for a TKO, we run one behind a 383 SBC that is injected and blown in an E type jag, Runs about 700 at the wheels with the tyres smoking on the dyno at 75% throttle. This car is used in hillclimbs, historic sprints etc, works great. This car will carry the front wheels in 1 & 2 if you want. No issues. It's the fist motion shaft that will fail in a TL with big power.