I'm sure you know that this will be a project for several months, if not a few years.
David has good advise.
I could argue to change ALL consumables, oil, batts, impellers, belts, filters etc. Be sure all sea cocks are in excellent condition... much easier to change on the hard. Change any old or suspect hose or line, especially fuel.
I'd look close at appliances, like water pump, alternator, etc, and be ready to change if they done work.
Check carefully for corrosion or obvious leaky fittings and clean up and replace as needed.
the goal to get as far ahead of the boat as you can in the beginning.
Also, did you have a survey and if you did, address the survey items.
Keep us posted.