Mast raising
First, regarding the plate: I would say continue with your search at the rigging shops. As a last resort, I'm sure you could either get the old one fixed at a welding shop, or as a last resort, have a new one fabricated. Drill the rivets out of the old plate (I assume you mean the one in the bottom of the mast). As for mast raising: I have read the many posts about how other people do it (with self-made tripod rigs) and so on. But since buying our 23 in 2001, we have raised and lowered our mast each year with 2 people without using any winch or mechanical advantage. First, we use a "stepping plank", which is really a pair of 2x6's which go from the top of the transom up to the cabin top. We screw on one 2x4 crosspiece at the transom, and one which is cut to exactly fit inside the slider channel (i.e., it sits on the slider track where the slider would sit if it were not pushed back) and takes the weight of the top part of the plank(s). We put the hinge pin through the mast at the mast step, with the mast resting in the mast crutch. (We had to make a crutch out of a 1x6 with a V cut in the top.) Then we tie a stopper knot in the (mast base) end of the main halyard and hook a spare jib halyard to the other (mast head) end of the main halyard. One person stands at the mast crutch (transom) and walks the mast up to vertical, while the other person stands far out in front of the boat with the end of the halyard tied around their waist and backs up slowly to pull the head of the mast vertical. This seems to work pretty well, with the stepping plank making it much more reasonable, as you don't have to hop around at the critical moment to get from the cockpit to the cabin top.
