I bought my 383 on October 25, 2012.... 5 years ago this month. A mistake I made that I didn't know to specify when it came to the surveyor: Be sure he is a SAILBOAT surveyor!!! While I told my surveyors I called what I was looking at, my guy told me AFTER he got there that he really didn't do any of the sailing rigging stuff... I was too far into it to stop the process...
Although none of the things I have since done to the boat were noted by my surveyor, the following are the things that I've since done to the boat, or have observed to replace/repair very soon after I bought the boat:
1. the Square D 30Amp breaker went bad (you have to be a contortionist to get into the helm seat hatch to reach the box to replace it!
2. the refrigeration quit
3. the forward freshwater tank leaks
4. the holding tank leaks (it is not a visible crack, it just oozes up out of the fiberglass of the tank's top where it tabs to the bilge wall... I have a video on Youtube that shows the leak taking place as I pumped the head when the tank is full); I have since had a tank made and put it under port settee and that issue is now resolved. I have a posting on the board here with exactly how I did my tank and plumbing... it works very well now; i sealed the old tank up and leave it empty...
5. port lights were brittle and leaky so I replaced with NFM stainless steel ports
6. the fixed ports over chart table and stove were crazed so I had dark tinted plexiglass made to replicate clear originals
7. mainsail while in great shape, I discovered really didn't fit the mast/boom (undersized) so I had a new sail made by North Sails; kept original main as a spare and the original Morgan main as a barely serviceable spare
8. Perkins diesel while strong running, has proven to be dirty, i.e. leaks oil around pan in rear and at front
9. exhaust, raw water intake, head, sink drain, etc... be sure to inspect all hoses... there are a lot of hoses in these boats and be sure to inspect them!
10. halyards and sheets... don't overlook inspecting all of them!
11. standing rigging... I didn't find out when mine were last replaced and a subsequent rigger checked them and said they are in good shape.. a gamble I took at purchase that I don't recommend!
12. Although I didn't do this, any owner worth his salt has maintenance records. Ask for to see them before making an offer. If they won't show them, then it's 'caveat emptor'... buyer beware....
I know i've done a lot of other things, including bimini, dodger frame and canvas upgrades, air conditioning, etc.... I hope this all helps or validates what you are already doing... Good luck and welcome to the board!!!