Sorry to hear about your bad luck with the engine!
The only thing I can suggest for solid data is to look at the prices in Yachtworld, or perhaps chat to a broker to see if he is willing to get you some comparatives/a listing of recent sales.
In my research, top-condition P323 are being offered around $30K, perhaps slightly higher. I have never seen one above $34K. I am not actively searching, so my data may be out of date. With the weak economy, sales tend to be ~20% below the asking price. Also most boats seem to be listing for 8-12 months plus before they sell.
From what I saw, a lot depends upon location.
Remember, if you want to repaint the mast, that means pulling the mast; if that has not been done recently, it will be a good time to check standing rigging (maybe re-rig), check chainplates, maybe upgrade lighting.
Without having seen your boat:
Original fabric, sails usable not new, blisters, new engine...unclear how recently standing rigging replaced...maybe list at $27K?
Fix blisters, repaint...maybe list at $30K?