I think you could use two of the same aftermarket steering shaft bearings and adapter bushings sold for cutting off and removing the steering box while retaining the upper part of column and steering wheel.
Actually with the column being cut off so close to the worm (already supported by two bearings) a 3rd bearing may be unnecessary, could use a seal to keep water out instead. May then need to vent the fill plug or otherwise vent the gear box.
After all that is there enough room left in between firewall and steering box for a couple u-joints and the collapsible section?
Finally when mounting bottom of column to the floor don't make that so secure you defeat the purpose altogether.
Worth the thought but not sure it's worth actually doing it?
Grigg