Sb350/th400/np205 drivetrain set up

[Furno68C20]

Hey guys and gals. I’ve got a 1975 k20 that originally had sb350/th350/np203 set up from the factory. I’m swapping to a th400 and np205. The 400 is a little longer in length by a few inches, which has basically moved the driveline back. My question is what length rear shaft would be the correct fit to accommodate this extra length, or do I use a 60”shaft with a shorter yoke?

Also the front shaft has also extended to accommodate the th400. How much can the front shaft telescope without having any drive issues?

Thanks!
Posted via Mobile Device