A belated welcome to CSC!

Charlotte Harbor is my favorite Florida cruising ground. If you get back down here, let me know. I can put you and your kids on some fun stuff.

Connnor

Thanks for the input. That got me thinking about what material I may have laying around. I had a transom reinforcement plate from a pontoon(1/2" aluminum) that I cut in half, put the top half in the splashwell, and the bottom half down in the bilge for the lower two bolts. It may not be a permanent fix, but it's a lot stronger than before. I took the opportunity with the old engine off to pressure wash the bilge, then got sidetracked with removing old wiring in the bilge. I am moving the battery up to the console as long as I'm cleaning things up for better weight distribution. I do get concerned with the 20" transom. Someone added a layer of plywood to the floor, and there are no more scuppers, so this is not a self bailing boat.
Thanks for the info on propping. I believe I have a 15 pitch Yamaha prop on there, so it may just work. I'm anxious to see how the 90 horsepower motor performs on the boat. I've always rigged engines with the cavitation plate level with the bottom of the hull, is it a Seacraft specific thing to put it 1.5" above the bottom of the keel?

Pretty standard on the 20 hull. more bang for your prop. not sure if your yammie is 400 lbs or newer light one, but I think up an 1+" will help.

Regarding the scuppers - did they glass over the scupper holes in the bottom of the hull?

I rigged the engine and am running into issues with steering cable routing. The obvious solution would be to cut out some fiberglass to enlarge the rigging hole on the starboard side of the splashwell. To get it at the right level it looks like I'll have to cut right up to seat level. I don't see any way around it, so I think its time to pull out the sawzall and grinder.
@Mcgillicuddy: I think the weight of the engine is 369. It looks like they screwed and glued over the scuppers in the bottom of the hull(at least there is some sort of plate down there).

Good deal on your motor weight. Light is right. If the plates are thin wedges that was standard practice just fore of scupper holes. Scupper holes would have been immediately aft, so my guess someone filled them.

As far as the steering cable goes a lot of these have been butchered to some degree. max flex cable might help. some models have a little lump on the edge of the of the stern locker and splashwell designed to make that easier but some were not conducive the driver's preference of throttle shifter placement.

Now that I look at it closer I see that I can't even enlarge the hole enough to get clearance. I need to cut a second hole where the starboard seat bottom meets the transom about a foot away from the steering tube on the engine. I'll arrange some sort of clamshell to cover it for now. I imagine this cable routing would be an even bigger problem on a raised transom.
The scupper holes appear to have been filled before the last coat of bottom paint went on.

Hi, Tommy - I ran into the steering cable issue on my 1972 Seafari - and found that converting to hydraulic was better than hacking up the starboard seat base and having a hard bend on a mechanical cable. here are before and after shots:

I cut the smallest hole possible in the seat, and will put a clamshell over it. I was able to get it so there are no tight bends in the cable. Your hydraulic steering looks great. I don't know how long this motor will stay on the boat, so I'm not going to go overboard right now, this is a bare bones setup. I want to raise the transom, which will mean a different motor. I'll post a picture once I figure out how to use my Dropbox.

Hydraulic Bulkhead fittings are also available for the hydraulic lines which will further "tidy" and clean up the transom area. Rigging tubes make a big difference

This is completely off topic, but is there any reason to save the original seats from this boat? I pulled the two pedestals off and installed a flip flop cooler seat that I had sitting in the shop. I like it a lot better, so I don't think I'll ever out those seats back on. Just wanted to see if there is any reason to hang on to them.