Ive been trying to find out a lot of the same information about the A750F bolting to the HF2A. From what I've read in several threads is that it will bolt up. Most of the threads are pretty old and it seems the reason the A750F wasnt a more vommon swap was due to the lack of TCU. It seems there's a Australian company that niw makes a TCU, but it cost about $3k (ouch).
So let me throw this idea into the mix.
1FZ-FE: 4.5 I6
212 hp
275 lb-ft
Weighs 584 lbs
2UZ-FE: 4.7 V8
232-271 hp (depending on year)
311-315 lb-ft
Weighs 500 lbs
1GR-FE: 4.0 V6
236-270 hp (depending on year)
266-289 lb-ft
Weighs 350 lbs
The 1GR-FE also came bolted to the A750F. The later years are 270hp, the early years can have a super charger added that puts out around 315hp. Theres also the weight savings and the fact that the V6 is shorter so all the weight should be over and behind the front axle instead of leaning over it. Or, since the engine is shorter, the engine and transmission may be able to push foward to run a doubler from Low Range without having to move the stovk transfer case. The 1GR-FE/A750F combo is in a lot of FJs, Tacos, and 4-Runners. Another bonus is that the 1GR-FE is chain driven as opposed to the timing belt in the 2UZ-FE. I know that matters to some folks.
Sorry most of this went off topic. Where i was trying to go was that given the V6 combo, Low Range sells a doubler that bolts to the A750F and to the FJ/Taco/4-Runner. Since the A750F bolts to the HF2A, it stands to reason that their doubler would also bokt to the HF2A. I have not confirmed this with them yet though.