I like George's plan to keep the existing 3-speed and use the 'glide torque tube and center section (assuming the axle splines are the same). All's you'd need is a flywheel and a pilot bushing for the '54 235 as I think your '46 bell housing will bolt right up to the later 235.
I lost my Patrick's catalog somewhere along the way but as I recall he makes an adapter to mate a torque tube up to a Saginaw 4-speed which would work well with the 3:55 gears. This could be done later on down the road.
I used a T5 from an '89 S-10 truck (NWC) and a rear end from a '70 1/2 ton to keep the 6 lugs.
