Brad
You need to talk with Frank - MoBetta - . He took a 21' Trophy I/O Redid the transom and put a Bracketted 115 HP Yamaha 4 Stroke on it . He would be the man to talk to . I know he loves his boat .
Now as far as dumpimg money into an older boat . There's some issues . Basically what kind of boat we talking about . There are quite a few older model boats that are worth putting money into .
Then there are quite a few that are not . Alot depends on you . Do you really........ like the boat , or are there ceratain things you could find on a different boat the same size that would be better for you ? Bottom line is you never quite get there , but always get a liitle Closer . I/O's are not always that expensive to redo , motor and outdrives . Now changing over to differnt kind is another story . The bracketed motor is an exceptional idea , but until you talk to some who has done it , and is willing to give you a complete cost breakdown for redoing . I would check out the cost of I/O's . I have an I/O in my boat now . Wish I had my old 2 stroke back . But , Big but , If I had to change an I/O out I would withour a doubt go desiel ! If you have a boat that is worth investing that kind of money in to, to begin with . Take the time and find out about diesel repower . Converting over a transom on a boat is a major deal . The bracket idea does sound quite fesible now that you think about it . It plugs uo the whole in the transom
I could go on and on but I'm not . Check out all your options .
Let us know how you do .
Michael