Yes, you'll be able to use the 240 parts. My friend recently completed a restoration of a 75 164E. It's got a 90 244 interior in it. Looks lovely. You need the spacers that go behind the panel- like blue or purple plastic nuts that are fitted into the door- that's what the door handle screws go into. You'll have to decide if you want the angled manual window handles or square power window handles. Late 240s (89+) are all power-window cars. An early car that's not a GL or turbo will have holes for window cranks.
You can use virtually any 240's parts. For the wagon rear parts, well, look for a matching wagon. There are a whole pile of pieces to change out back there, including the cargo floors and spare tire cover. Enjoy!
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Rob Bareiss, New London CT ::: '87 244DL/M47- 221K, 88 744GLE- 202K, 91 244 181K, 88 244GL 145K