to nautidog and ianper. This may get lengthy, Gentlemen but here goes, for what it's worth to you.
First off, I prefer what I have over any other type of power setup and it can be done to any boat whether inboard outdrive or outboard against the transom.
My Grady was originally an outboard with the usual outboard cutout in the transom and the little pitiful transom panel to keep waves out of the boat. Found the transom to be rotten when I noticed a little movement as the engines were tilted. It was all just a little too bouncy. Took the little trim strip off the top of the transom back there and there was an opening between the transom and the top (or cap if you prefer) I stuck a tig welding rod down it and almost lost it. Incidentally, I recommend the opening be sealed with fiberglass on any boat that has the seam under the aluminum strip. It just doesnt stay sealed and that's where the woes usually begin.
A friend and I cut the transom out leaving about 3" of the original glass on the outside perimeter to retain the shape of the back and for something to bed the new transom to. I built a FULL transom, putting a bracket on the back and getting the engines out of the boat and being able to discard the flimsy little transom panel that Grady provided. Not a good design for them on that. So now thew boat can take a wave back there and I can back down on a fish hard as I want to.
I built my bracket myself after a fiberglass repairman in the area let us copy the dimensions off one that was commercially made. I used 5052 grade aluminum and migged most of it with 4043. worked ok. I tigged the outside welde where pretty counts. I welded it up and it works good. That was in 1995. I had two 200 johnsons on it and things went really well until I repowered last year with Suzuki 225's.( Yep, overpowered, but you dont have to use it just because you got it) These guys weigh a little over 500 LBS each. My bracket is 28" out. That length was for tilting clearance and was the only factor I considered when determining the amount of setback. (hint, hint)
Now the boat squats in the stern about another 2-21/2 inches deeper than it did. It's most apparent when running rough water because without a lot of tab hanging down the boat is way high in the bow. Not so good for handling rough water. So now, I am building a bracket which is a near copy of the later versions of the grady whites. At least it'll go all the way across the stern and provide a lot more lift back there. (nuther hint)
Armstrong makes a bracket which is good. Their url is: http://www.armstrongnautical.com/brackets.htm
kinda pricey but you get what you pay for. I recommend them and I am not positive but I think we used templates off one of their brackets for mine.
Some things I did that may have been overkill was I put a laminated beam inside on the front of the transom at the level where the bracket bolted on. The beam was about 4" thick and 6' wide and tied into sides of the boat for a little ways, maybe 6-8" out.
I put fiberglass blocks at the bottom of the transom where hte trim tabs screw on to eliminate water seepage into the transom wood. And I was particularly picky about drillling and bedding any hole I had to put in the transom. There were over fifty holes (yessir, I counted them!) drilled into the original transom, most of which were unsealed. That's shoddy dealer and manufacturing practices, plain out! I wrote a kinda ugly letter to Grady White about that. Just no excuse for it.
Anyway, the boat is still at it. Bracket is good, Transom is great and I'm sending the ol' gal in this fall for a complete makeover new topsides, check stringers and add some goodies I've always wanted.
I can completely rebuild for a fraction of the cost of a new boat and this boat is, in many ways, better than most nowadays. The hull is almost 3/4" thickon bottom, didnt know that.
I'd try to answer any questions you may have that I can answer. If I dont know then I'll tell you I dont. I prefer the way my boat is set up over any other I've ever been out on. Just a good functional setup.
My welding is purely vocational. I occasionally built a hard top or t-top for someone, I've built a few brackets ans I mostly have a good time working metal. I've welded for a living for much of my life and am a retired BP welding/ pressure vessel inspector. I'm 62 now. so, I may be give some sense to your welding questions if any.
Hope I helped you. Sorry it's so long but there's a lot to say and a lot more that can be said.