Scabbing a transom to raise to 25"

[Greno]

Anyone done it. My transom has been replaced previously and is rock solid. Anyone scabbing in a dutchman to raise it and how much bracing into the coring did you go. I think my old johnson has had it and I have a line on a yamaha ox66, but I need to have a 25" transom. Rather not have a jack plate. I have a 1979 18 and the transom notch is very low freeboard and I would feel better having the more freeboard. All comments are welcome.