81 and newer SM465, then bolt up an IFS (drivers side drop) NP241.
You might have problems with finding a hydro bell that works and has the slave on the passenger side. Most (if not all) 465 bell's have the slave or linkage on the drivers side and it would interfere with the front driveline for you.
A better swap would be a NV4500/NP241. It would be almost a direct bolt in deal. You'd get the overdrive as well as a granny low first gear, and the factory bell would work. You could even swap in a 32 spline input into your existing T-case and bolt it up without any trouble at all.
You will need the clutch pedal, clutch master and clutch slave for your era truck too. You may also have to cut an access hole for the shifter in the tranny tunnel. Most likely the tunnel is already dimpled for the shifter from the factory.
Rene