Yeah I did the same thing this week, but with a ’57 Johnson QD. Then you will have needle bearings, instead of bushings, other than the center main. Beefier rods too as mentioned.
It’s been my experience with seized motors that the crux of the problem is always the bearings .Usually getting the pistons to move is not that big a deal but often it’s at the expense of scored journals due to totally seized bearings .Now 98 percent of my stuck motors got there because of saltwater immersion and a good portion of those were running when that happened so chances of any real success are pretty poor from the start.If you are lucky enough to live in one of those "Land of a thousand lakes " places you’ve already got a leg up and if the motors you come across show good cosmetic signs so much the better ,as for me I’m heading to the recycle with a half ton of motors that should have been salvagable but just aren’t worth the effort.