[bitsamonkey]

I'd like to respectfully disagree with some of the advice given. My 20' seacraft sank over a year ago and spent 10 days bouncing around the ocean floor before I was able to recover it. I was able to save my fuel injected outboard and am still using it on another boat. I did have a bad atmospheric pressure sensor and I replaced the O2 sensor, but those are the only parts I replaced! Everything else still works (I did go through absolutely everything and triple rinsed, dried and lubed it all).
I know you stated that the motor is seized, and that's a shame. If it had been worked on immediately after being recovered you probably could have saved it.
As far as the hull? Well it's a '74 and has probably been sunk at least once in its lifetime, they don't call 'em "sinkcrafts" for nothing. What are you worried about? Rinse it out, let it dry, rewire and voila!
If you had hydraulic steering it'll be fine. The gas tank can be flushed and dried out as well and use a good racor when you're done.

As to why it sunk in the first place? Imho these boats are not fit to be moored or docked unattended as they are barely self bailing and have super low 20" transoms and lots of cutouts in the motor well. When mine sank, the guys that plucked us out of the water had their own story of a 20' seacraft sinking!