I know this is an old thread, but just for anyone's future reference, as a former Honda dealer mechanic for many years in the late '60s thru 70's, and also speed shop mechanic early '70s, our fix for frozen motors due to water/sitting too long, take out the plugs, get any water out with air hose, spray your favorite penetrating oil in there ( our fave was LPB parts blaster ), give it a day or maybe overnite to do its work, then remove the dyno cover, grab a breaker bar and the proper 6-point socket, and patiently work it back and forth. It should loosen up after a bit, and when the starter will turn it over nice, blow out what you can from the cylinders, spray in a little starting fluid ether, and fire that mother up. Always nice seeing that rust-colored mess fly out of the exhaust.