Professor,
I tried to go with twin 115 suzuki's on the back of my '78 cc and it didn't work. Even with a 30" transom I took water over the back and those motors weigh 832 combined and I moved my batteries under the console. My current setup is a completely closed transom and a Mattson bracket. I also went from a fuel tank that was 155 gallons and 8 1/2 feet long to one that is 103 gallons and 5ish feet long thus moving more weight up front. I can keep my scuppers open but choose not to as too much water will end up in the boat. I don't sit stern low but I do wish my bracket had another 200lbs of flotation.
Long story short, I love my setup and would never ever consider going 50+ offshore with an open transom.
My opionion is to do the job right and get a good bracket and if you need the power get 150 or 175 Suzukis. I don't like the idea of you offshore with a single. Now the question-----are you ready to spend 30k on this project?????
PS you will love the ride of the SeaCraft even more with a bracket.