Two-piece column and "adjustable" steering wheel are two different topics. The "adjustable" wheel was an option on both early and late cars; but there was a change point for the "split" column (which was apparently instituted to make it easier to assemble the cars at the factory).
Moss gives the change point as approximately TS42000, but TS39781LO had the split column (with a fixed steering wheel).
In other words, there are 4 distinct steering columns:
1) Early single piece column with fixed steering wheel
2) Early single piece column with adjustable wheel
3) Later split column with fixed steering wheel
4) Later split column with adjustable wheel.
(Well, actually 8 variations, since all four of those come in both LHS and RHS versions
)
The early solid column should fit later cars I believe (with the matching steering wheel of course); you can just leave off the extra brackets. But you would have to add brackets to an earlier car to convert to a later column.
Adding the brackets might be no worse than drilling holes and adding bolts, but I've not looked into it in detail. I believe the factory added captive nuts to the firewall, and welded a bracket (actually two brackets, one each side) to the frame.