You won't get close to a new outboard for $5800 (not a 200, anyway). And you can get it done for less by a qualified, trained tech.
From personal experience, don't put it back on the water without getting the ECU checked by someone like Rapair, Brucato or Simon Motorsports. My '93 seized twice on 2 different cylinders. The mechanic that rebuilt it said he checked the injectors, and they all sprayed perfectly. Merc rep said to send the ECU to Rapair, and they sent it back with a bill. I asked them what I was paying for, and Sean told me the injector drivers where all bad, and several solder joints were bad. He said it was common for that particular ECU. I never had trouble with it after that.
Dad took me fishing when I was 10, and I've been pretty much hooked since. He went to be with God on August 14, 2012. I miss you, Dad.