So you do understand the 2 or 3-1 ratio of what it may cost to update a used boat. I would bet the motor alone for you Ericson was 50-100% of the base cost of the boat! Much less repairing the rotted wood work etc. I know a new motor for my boat would be 5G in and of itself, much less the labor to repair it!
The numbers above would be appropriate for a 35-10' boat. Frankly, if you do not want the possiblity of doing to the new boat, what you did to the ericson, you had better upgrade to a 1990 or newer boat. UNLESS, you can find a boat that someone has recently gone thru. Otherwise, yes you will spend 2-3 yrs, 2-3 times the cost of the base to fix it up! Not 20%. A decent set of dacron sails would be close to 3 bills for my boat alone! Much less the 4G ea for a string main and 155 genoa!
I will also add, down below my boat does not look like a racer, it is quite nice! after the 80-100+ hrs redoing the inside. you can see before after results Here
along with here
For being 28' on deck, the boat is not too bad inside! Granted it does not have hot and cold running water, but many boat of that size in that time frame did not. Later and bigger yes.
From my experience with this boat, and tales as you have, go newer! Unless you want to spend time repairing. Yes the base fiberglass of an H37 is sound. The rest, including a Gin Fizz, will need some help unless you can find one, someone did all the work, could not finish the trip, get to it etc. The Tartan 3500 next the H37C on my dock, at 100K would be a better buy overall. You could probably leave tomorrow per say down the left coast where I am to mexico. I would not recommend it, as there is gale to hurricane force winds forecast for the next day or so.....but that is another story. Then again, being as the T3500 has 7.5' of draft.... you might not like that either. nor the 5.75' my boat has!