Re: 1982 Sea Ray 225 260hp kicker motor options, w/swim platform
You probably already know what needs doin'... but I agree it's a fairly big job if you don't have easy access to the inside of the transom.
Remove platform, brackets, and supports from the back of the boat. Fill all holes (checking transom for rot while you're there).
Fabricate new HD supports and brackets. Thru-bolt everything and seal well inside and out.
The platform itself is probably just fine. Good time to give it a coat of Cetol, too.
BTW your boat looks to be in fine shape. Gel coat shines nicely.
Alternate plan -- I've seen motor brackets that attach directly to the outdrive and hold the kicker back behind the main prop. My uncle had one in the late '70's (not saying that I've seen once since, however). May need to cut away the aft area in the center of the swim deck for clearance when in the full-up position. He had two separate swim steps, once on each side.