Terry, remember the 21's were very well built and survived some very rough offshore races w/o problems, which means they've got lots of structural margin for normal use.
I'd be real careful about ripping something out just because it's old, unless it's obviously rotten like the front deck. At least do a little exploratory surgery first. I will forward your e-mail with the photo's to Bob to see if he had any problem areas on the Unohu that you might want to check out. Fresh water is worse for causing rot than salt water, so whatever did not rot after all those years of exposure to fresh water, is probably ok for salt water. Big Shrimpin's right, it's easy to CREATE problems if you're not careful. I'd put the emphasis on fixing enough stuff to get it operational, and then use it for awhile to get a better idea of what you might want to change. I'd hate to do all the work involved with a full restoration and the later regret that I had not made some significant modification that I thought of AFTER using the boat in it's original configuration! [img]/forum/images/graemlins/tongue.gif[/img]
I do like your idea of a jack plate instead of a full bracket, although that boat was well balanced with a 1000# outdrive, so a bracket and a single V-6 2-stroke would probably provide similar balance. If someone like Fr. Frank on the forum knows the weights of the old outdrive leg and engine, it would be fairly easy to calculate the equivalent moment for an outboard set back off the transom.
I used to have a kicker with a parallelogram/4-bar linkage bracket on my previous boat. Might not be hard to make one and rig it up with a hydraulic cylinder. There's an outfit in the midwest that makes jack plates and trim/tilt brackets; will see if I can find a web site for them. Denny