Unfortunately I don't see ANY way a LS series mated to an auto trans will fit into the DeLorean frame period. This is just my opinion bc as many said, if you have enough money....but frame wise, I don't see it. When I was doing my swap back in '01, I wanted to put a LS6 into mine. (Mine was a auto DMC at the time) With the custom bell housing (or even the bellhousing shown above; which I believe is an auto setup) mated to that Porsche transaxle, I don't see all that fitting into the DeLorean engine/trans area.
With my 4.3 mated to the auto, I had to run a short water pump and STILL had to notch the rear fascia just to get it to fit. However, that being said, when the auto trans crapped out on me, and I found the Porsche 915 transaxle, the bell housing size went to roughly 3/4 of an inch!!! PLENTLY of room to drop a LS series engine in there now with the manual 915 but the 4.3 has so far been COMPLETELY bullet proof and....well, if it ain't broke I'm not gonna fix it. I have decent power and no issues whatsoever but when the 4.3 does finally go, I do have a spare LS1 engine that I'll drop in at that time. (recently swapped out my LS1 in the Vette so I have the spare)
So in short, if you're lookin at a LS series engine, manual is the way to go and if you go stock DMC transaxle, your weak point is going to be the input shaft. If you go with a 915 or G50 Porsche trans, you'll be good to go.
Hope this helps