In case you’re not aware that Fleetwin’s reply has appeared, here it is. .
OK, so you are saying that the crankshaft is seized into the lower bearing/seal assembly? Were you able to remove the four retaining bolts for the lower seal housing? Did you remove the piston/rod? If so, that crankshaft will just push out of the bottom of the crankcase taking the lower bearing assembly with it. It might be best to place the block in a press to drive the crank/lower bearing housing out of the block. Once out of the block, you can flip the crank/bearing housing upside down, put it back in the press, using a simple spacer sunk/bottomed into the crank splines protruding out the seal housing to separate the crank from the seal housing.
Unfortunately, I’m guessing neither of those two parts will be much good. Going much further with this project seems like a questionable endeavor unless you just want to enjoy resurrecting one of these engines. What condition is the rest of the engine in? Fresh or salt water use? The critical piece on this thing is the darn steel fuel tank. You are pretty much SOL if the tank is rusted/fouled, although I have converted one of these engines to the newer style with the plastic tank.
The best bet here would be finding another 2hp with a decent powerhead, but they are getting more rare and folks seem to think these things are “gold” they way they price them. Just keep looking on CL/FB, something will turn up for a reasonable price.
Keep in mind that these engines have no oring on the upper driveshaft to protect the splines, so worn/rusted splines are common. The best powerhead on earth is useless if the crank splines are rusted/worn/spum out.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.