keep in mind that what keeps automatics alive is line pressure...shifts gears, engages clutches, who knows what else. line pressure is rpm dependent, and a gas auto turning at diesel rpm doesn't make the same line pressure, which is a big reason gas autos don't live behind diesels in swaps. automakers could run more line pressure than they do stock for reliability, but that makes trannies shift harder,which the public has been trained to avoid. I think the A440's issues in FJ62 are likely the result of lower than ideal line pressure from the factory. that has to be compensated for if you put a high power at low rpm motor like a 4HE1 ahead of an A440, such as with the Aussie valve body...make sure they know you're putting a grunt motor in when you talk to them. Orange45 could talk much more intelligently than I about this, as he lived and breathed autos for years, but there are a lot of slippery A440's out there that would probably get murdered by putting a 4HE1 ahead of them with no other mods...not to mention the high-stall torque converter. imagine driving a diesel, and only engaging the clutch from a standstill at 2200 rpm...that's what a high-stall TC is like. I drove an '89 Dodge Cummins with the 727 (I think) three-speed and basically a gas motor TC, and it was like giving all the low-end torque of that motor away...
Now, I'm no expert, so flame away, but IMHO to put a 4HE1 in front of a high-miles A440 will result in tears down the road.
Don't let the fact that I hate slushboxes affect your reading of this in any way
I like the idea of a 4HK1 ahead of an NV5600 or other 6-speed, but that's dreaming
I must say that when you hear a late-model NPR with an auto run down the road, you can tell the auto is set up right...and it's one slushbox I could see having.
Steve