Help: Sm465 heavy duty upgrade

[75chevycrewcab]

So have a 75 Chevy crew cab that I plan on swapping a first gen Cummins into in the near future and I'd really like to use my sm465 that's already in my pickup. So I'm looking for any heavy duty upgrades I can do to it to be able to handle the torque, I plan on building the diesel up to around 800 ft-lbs and need to build the tranny up with heavy duty shafts and such. Any info anyone has on a transmission build or even my pickup build will be greatly appreciated. I have found other threads but they are all old so I'd like to make sure the info is still up to date. Also I will be getting a gear vendors over drive to bring down rpms a little.

Thanks for your time. Kodee