The easiest way to do it is to just get a later model rear end and run a slider yoke in your transmission, have a driveshaft made for it. To run with the origional suspension, you will have to split the wishbone, put either ball joints or spherical rod ends on the two wshbone shafts, find the proper spots to hang them on the outside frame, and then run a panard bar. The alternative is to convert over to dual semi-ellipitical leaf springs.
The closed driveshaft acts as a torque arm for the rear end as well as to enclose the drive shaft.
I think the ford pickups used the old style trans up to 52,my dad bought a 52 p/u motor with the trans still attached for his 51 2 door sedan and the trans looked like a 40 to 48 except it was made for a open drive shaft. I dont have the trans anymore or you could have it but if it was my car and wanted to keep the original motor I would adapt a newer trans and find a later rear and weld the buggy spring mounts to,a more modern trans will make cruising alot better as I am fighting a original trans and rearend in my 37 chevy p/u.