transom on 23's

[Jeckler]

Looking for a couple answers.I have noticed some transoms on the older 23's are straight across.Others drop down where the engine is located. I believe the boats with 2 engines are straight across. Single engine boats drop down.Did these older 23's come stock with notched transoms or are they reworked to accommodate 25" motor. I'm looking at one with 2 motors .I assume to go to a single I would have to look for 30" motor.Is this correct?Thanks