From my limited knowledge that refers to a powehead that is essentially two powerheads of two cylinders each. My 1982 50 is like that, two twenty hp stuck together with some other changes to get to 50hp
Welcome to the forum.
As stated, not the best boat and you will not never nope turn a profit on restoring it.
If it's your hobby, go for it. I had a 2150 L Drive, really liked the boat and how it handled.
Mercruiser all the way.
Oh and on the transom tilt motor up and push as hard ad you can down should be zero flex and try to tighten motor mount bolts should not be able to move much at all. I had a boat once was able to get a few turns then noticed the washer had sunk in meaning transom was rotten.