Look for water intrusion in the anchor well, as well as the line holes (most have been abandoned) on the right of the anchor well....also check the stainless hand hold attachment as well as the fore hatch (above the vberth) for water intrusion. Not a big deal, but check.
WIndows would be next to check, as they are nearing their useful life, both the mount and the material. Time (expensive) to recaulk, as well as $$ to replace the material itself.
Check for water between the aft berth and the lazarettes, most will have some degree of water intrusion (see it on the wood, as stains).
Biggies for me, after having owned one, is the repair history...have the tanks (fuel and holding for sure, water maybe) been replaced, if not plan on it. Same with the water lines and fixtures. Batteries are tough to get to so make sure they have been maintained, same with the genny.
We loved ours, and lived aboard for several years. Nothing else, or major jumps out.
They are tough to slip in wind or current, so practice some when you move up from the 35'. We hired a captain for a couple of days for both of us to practice, with out being too critical of each other.
Best of luck, for sure email or post if you need more particulars. We had the P42, 1991 model.