There a couple of factors to consider. First, do you like the boat design? The Cherubini Hunter 33 has a good reputation but it is an old fashioned design, narrow beam, narrow stern, limited light. Those things you cannot change. It could be good for offshore work but you need to factor in replacing worn out parts, storage, sailing performance. Second, what is the condition? Not only the rigging, etc. but also inside. I have a slightly newer Hunter 31 and I happen to love its particular design/layout/space/sailing performance, so for me the investment in time and materials was worth it. Yet, there are parts of a 40 year old boat that you cannot easily change. The cabinetry is slowly falling apart. The cabin sole will eventually need replacement. The gelcoat is worn out. At some point, you just need to buy new, there is no point in maintaining an older boat. The motor is not such a big deal. You can get a second hand Yanmar diesel with plenty of life left for $3-4,000 and it will be a drop in replacement, you can do it in one weekend.
One factor to consider with "cheap" boats is that you will be spending around $10k/year on slip fees and maintenance, even if you got the boat for free. After five years, you will be out a minimum of $50K but you will still have a $20K boat. It does not compute. Once boats go past 30 years, the residual value is minimal. It may make more sense to get a $50-60k boat instead. The key factor is, do you like the boat. Spend a couple of hours in the cockpit, etc. and you would know. We can't help you here other than share our thought process.
In my case, I settled on headroom (needed 6'2") as my primary criterion, found some boats that I liked (i.e. HR 31 would have been the perfect boat for me), spend some time to understand what trade-offs designers typically make (for example, deck stepped masts are better because the saloon is much neater, forward head vs. aft head, etc. and then started looking for boats that would have as many of the criteria of my dream boat as possible for an affordable price. Four years later, I could not be happier with my decision given my use of the boat and preferences. So, do not buy a boat because it is cheap, buy a boat because it makes you happy.
SV Pizzazz