I've had a little experience like this. I kind of went the other way: I put an engine from a 1989 240 (LH2.4) into a 1988 740GLE (LH2.2).

The really key thing here will be whether the new engine has a drive gear for the distributor. If it does not, you will need to replace the intermediate shaft. Fortunately, it's a part that does not fail, but you would need to get it out of the existing engine (I assume there IS an existing engine).

The cam plug for the back of the head is no problem. With the engine out, remove the 740 dist (Sell that thing here or on ebay, lots of people have hall sensor issues!). Install the new cam plug for a 240 engine. They cost like $1. Tap it in, no issues.

Getting the old dist plug out will be fun. It's driven in, and likely rusty by now. In my case, I was removing a dead 740 engine (dropped #3 exhaust valve, very destructive) and needed to plug the hole in the 240 engine where the dist used to go. So I wanted to save the plug and didn't care about the block. The block cracked really easily at the front corner. You want to save the block and don't care about the plug. I would drill into it and maybe try using a slide hammer. Once it's out, use a magnet on a stick to get out metal chips. You may want to try washing the remaining chips down into the sump with some brake cleaner or something, and then changing the oil prior to running the engine.

Anyway note that the plug is made of some pretty thick metal, and it's going to be quite stuck. I don't really have a good answer for removal, just be patient with it so nothing bad happens to the engine.

As for the rest, you'll have to change a couple sensors because temp sensors have different connectors in LH2.2 or 2.4.

The flywheel, you'll want to mark both engines at TDC to swap it correctly. You need the flywheel with the holes around the edge (windows in ring gear for the automatics). You'll also need the crank sensor mounting bracket up over the flywheel. Put it on after finishing other work, as it will sort of be in the way. You can install the crank sensor afterwards but access is bad on a 240.

Good luck with it, there are about a million other things like ALL the accessory brackets and ALL the engine mount hardware to swap over but I'm sure you'll see exactly what's needed and what's the same.
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::: Rob Bareiss, New London CT ::: 92 244 ::: 90 745GL ::: 90 745T ::: 84 242DL ::: 90 745T Parts ::: Used to have : 86 244DL, 87 244DL, 91 244, 88 244GL, 88 744GLE, 82 245T, 86 244DL, 87 244DL, 88 245DL, 89 244DL!