Hello Tas, we've got hundreds of Australians here, several New Zealanders but we dont hear much about Vintage MB's from the Island Kingdom of Tasmania.

Heck, wider SEL door panels going into your SE should be no problem..... seems to me that any skilled craftsman can narrow the backing and retuck the leather - even using your original SE door panels as template for exact sizing.

But the real question is whether or not cut-outs for the window crank, door handle and release catch line up

Give it a try, says me, especially if you've got electric windows where the window crank wont be an issue.

If your '68 has console switches, but the new leather interior has em on the doors then so what? Just leave the dummy door switch there to fill the hole and fake out back seat passengers.

(edit: And pick up the famous 109 tachometer and its sending unit while you are at it!!!