The tilt/trim problem is the cylinders that actually move the motor. They are simply hydraulic cylinders just like on a tractor or excavator, just different size and shape. I have been working at a hydraulic repair shop for 24 years now and we have repaired a number of Mercury tilt and trim cylinders. I have even gone through a few of the power units. Anyway, just take those cylinders off the boat and over to your local hydraulic shop. They will fix them without any problems. No need to buy new ones, the old ones are completely repairable.
Also, I wanted to ask you a question if you don't mind. I am rebuilding an '81 Bass Tracker II and am interested in painting it similar to the newer boats. I see that you did that with your other 2 builds. In the pictures of one of them, after you redid the transom, I noticed it looked as though the interior area under the transom had been shot with primer maybe? Did you paint the entire inside of your boats or just a few spots? Or was that galvanize spray maybe?
And the wiring. Did you run wires under the floor or along the side of the boat. It's been a long time since I ripped the wiring out of mine and am not sure where it was originally run. Yes my boat has been sitting in a pasture for nearly two decades. :| About time I finally got back to redoing it. I will get a thread going here as I have some pics of the work so far. New transom is in and getting the back end aluminum reattached/welded. Also trailer paint in the next week or so.
I think you did an incredible job on your rebuilds and they have certainly inspired me to get mine done.
Have a good one.
Larry