You can certainly outfit a small boat for off shore travel. Plenty of folks have been across the ocean in 25 footers; although, often of greater displacement. The Pardey's Seraffyn displaces about 10,000#, for example. I will also second the recommendation of the John Vigor book. It even has an appendix where he itemizes outfitting a Catalina 27 for offshore cruising. I wouldn't say small boats are less safe for crossing oceans, perhaps just less comfortable
. You do need a properly outfitted boat, of course. Heck, folks have taken row boats across oceans....
I would carefully look at other small boats that are on the market that might have already been outfitted partially for such work. Still, you'll probably have to do a good bit to get any boat ready. Personally, I'd be careful not to sacrifice seaworthiness for headroom. In this size vessel, it can be a real trade-off. In the meanwhile, try to get shorter
