If you have not yet settled on a surveyor, I would strongly suggest using Chan Chapman (
http://chapmanmarinesurveyor.com/default.aspx). He is vastly experienced and has crossed oceans. I don't work for him or with him; just a good friend. but I value his opinion.
I'd worry about the rig:
If the rigging is original or close to original I would seriously consider some work there. If the boat has swagged terminals I would definitely magniflux them and consider new main shrouds and a new back stay and fore stay with stayLok terminals before crossing the Gulf. I would pull the main chainplates and inspect their condition and the condition of the bulkhead or knees they mount into. Also, if the boat has cast aluminum spreader sockets--tubular spreaders would mean she probably does, then I would definitely replace them (
Rig-Rite Inc. - Masts, Booms, Spars, Rigging, and Hardware for Sailboats. has replacements) before doing the passage.
Obviously there is a lot of commercial traffic in the gulf. An AIS receiver would be very helpful.
I would assume there is a lot of crap in the bottom of the fuel tank. You should have no trouble finding a service that can clean your fuel and your tanks. Carefully inspect the fuel fill hose to your tank and make sure the clamps are strong and tight. Make sure you can blow thru the fuel tank vent. Same for the water tank. Seal the fill caps with tape or caulking before you make the trip as I'm sure the old fills are no longer water tight.
make sure the motor mounts are strong and tight.
Not sure if she has been repowered, but make sure the exhaust system does not leak carbon monoxide into the cabin when the engine is running. If you can smell exhaust in the cabin, then it is.
I would look closely at the packing gland hoses and clamps for the prop shaft and the rudder post. Also a close inspection of the steering gear, rudder stops, etc.
Make sure the water tank holds water. Bristol used stainless steel water tanks in many of their models and the older boats often have pin holes in the tanks and leak badly.
Inspect the old roller reefing gear and make sure it works. Be absolutely sure you can reef the boat properly. Look for signs of stress or cracks in the gooseneck.
If she has the old South Coast style winches, make they are not about to fall apart or partly seized.
I would get the compass swung. You can find that service in the Clearwater area.
Good luck. It should be a great trip