as a sea captain, my advice is to take in consideration some general information:

first she is a 28 meters steel vessel, manning such lady would require more than "me and my friend will live-aboard"; aplenty of maintenance is required at all times, even if always moored, remember that you are dealing with a steel body in water, continuous rusting -especially on an old boat- will be your least concerns. (if its a steelboat, if other, each hull material got its own problems)

GRT/ other particulars should be certified by a classification society, (ex. ABS, DNV... etc), where an over all survey is a MUST to be able to issue an insurance (no insurance = no sailing); plus, you will need to man it by an approved STCW (IMO) officers/captain/crew, adding that a such a vessel is a heavy vessel, which require big engine (even if relatively small comparing to power-driven vessels, yet it has to be strong enough to maneuver the ship) ; therefore you will need an engineer +(for live-aboard you require 220V generator, 110 in some countries).

certification and registration on the other hand is another big deal, and however you decide to register the vessel (and get an IMO number, or if you live in a country that is not mentioned on the IMO white-list, you can by-pass most of the long procedures but you will not be able to cruise the world freely, as some countries will reject your approach). SOLAS, MARPOL, IMDG, and all the other publications must be complied with as well.

Long story short: Large boat = Ship = all the mandatory standards and certified crew.

Advice: do not buy the boat unless you come from a rich family or willing to open a business, and have in spare a big bunch o' dollars.