I bought a Gulfstar 37 aft cockpit in September. I absolutely love it. I'm now living aboard. My surveyor said it was suitable for sailing to Bermuda, and my rigger (who has completed a circumnavigation) said he would feel comfortable circumnavigating in it. My ambitions do not extend that far, I think Bermuda or the Caribbean is my limit for this boat, but this is my first boat and I'm very inexperienced, so perhaps I'll get more bold with time. The hull and deck seem to be built very solid. The deck is cored, but on my boat there was no water intrusion (apparently this is rare to find in a GF37). The hulls are known to blister, so you will probably want to apply a barrier coat of epoxy (one of my spring projects), but if it's solid now after 30+ years, it probably has had all the blisters repaired or wasn't one of the ones to blister in the first place.
I think the interior is second to none for this age, size and price range. It has tons of storage space below, and the lazarettes are cavernous. It is a very fast boat -- I have regularly sustained 8.5kts in moderate winds (theoretical hull speed is about 7.5kts). With my limited sail-trimming ability, I can only get it to point about 55 degrees off the wind, which still isn't bad IMHO.
The only problem with the boat I've had so far is the water tank... it's fiberglass, molded into the bilge. You can't clean it due to the placement of the baffles, and you can't replace it without ripping out the entire sole and possibly compromising the structure of the boat. I'm determined to drink my tank water though, so I'm currently building a really nice filter setup.
The listing broker of my boat used to work for Gulfstar, and he was also a Gulfstar dealer when they were new. He gave me a detailed history of the company. He told me that there three distinct phases of management of the company, with the first and third producing very poor quality boats (mostly motorsailers) and the middle phase producing very solid and good-performing sailboats, and that is the phase that the GF37 falls into (~1976-1980). Also, I was told the GF37 was one of 3 differnet length boats (up to the GF43) made from the same hull mold, the only difference being the shorter ones essentially had the stern chopped off. This gives the GF37 the waterline length and interior space of a 43.
1979 Gulfstar 37 Laissez Faire