What model number Sportwin? There were many different types, spanning decades. Generally speaking, the idea would be to put a strap wrench on the flywheel and see if it breaks free. Do NOT, NOT, put a breaker bar on the flywheel nut and try to turn it that way. There is a very high probability of destroying the flywheel, if you were to do that….If it won’t break free and turn with a strap wrench, then in my opinion, the power head would have to be removed and disassembled. Like Dave says, by all means, remove the lower unit and see if it’s the gear case that is actually stuck; but with an Evinrude, my money is on the power head.
10024M is a 1962 Evinrude 10hp Sportwin. According to a nice member above that found it for me.
