yamaha 150 4-stroke prop?

[Briguy]

My fins on my flats boat are 1" above the transom. On my 23' they are about 2 1/2" above but I have a 29" setback.

Yes, having the fins at the same level as the bottom of the boat is what the old rule of thumb is but if you have good water pressure and no prop blowout raise it up as high as possible. Steering will be easier, less drag, less draft, better mpg, higher rpm. Boat dealers will almost always mount the motors on the lowest hole. Low liability.