Going back to look at your transmission mods. Is the 4HP24 in the rangie electronic control, and is the gear selection still on a rod change?
Seeing as you've put a 505 bellhousing on, can you comment on the relative sizes of the rest of the body and output setup of a 4HP24 and the 4HP22 from a 505? Do you think it would be an issue using the electronic controlled box in a 505 (I've found a controller)?
Yes, the 4HP24 is electronically controlled. It has a manual gear selector rod that selects P/N/R/D, but once it's in D the computer takes over. With no input from the ECU, it defaults to third gear.
The 24 is 15mm longer than the 22, but the body is the same diameter.
I'd need a pull a 24 apart to confirm whether the 'back ends' are interchangeable. I suspect if you use the output shaft and extension housing, you should be right. On the Land Rovers, the part number for the rear housings are the same between the 22 and 24, I'll have to check the output shafts.
Any electronic controller should manage it OK, it is just a speed sensor and 4 solenoids - pressure control, TC lockup, and the two gear selector solenoids - which in combination give you 4 different gear selections.