Is this the Nordica 30, the double-ender that was manufactured during the late 1960's/early 70's? If so, these boats were loosely based on the older wooden Goetenborg Flyers and Tumlararen, which were highly regarded for their seaworthiness and ease of handling. That said, any 30 footer is on the small size in terms of carrying the kinds of consumables, gear and spares that it takes for long distance cruising. And that said, if I had to pick an inexpensive 30 footer for a circumnavigation, this would certainly be a good choice.
Of course, even though these were a good design, they are a bit long in the tooth, and were intended for coastal cruising. Given the small size of the boat for this purpose, you would be need to commit to a more traditional style of distance cruising, which tends to be simplier and more spartan than many modern cruisers seem to prefer. Personally, I am a fan of this style of cruising, but its not for everyone.
Because of the age of the boat, and design, you would need to make sure that you have the key systems in sound condition. I would suggest that if I were contemplating a circumnavigation of a boat like this, I would start by replacing the standing and running rigging, replace the sails with sails that were intended for offshore use (heavier fabrics, chafe and attachment points.) I would beef up the rigging attachment points, hardware mountings, and add solid attachment points and jacklines for your harness. I would make sure to that you have a reliable two line reefing system for two reef lines plus a good set of storm sails (jib & trisail with own track). You will need light air sails as well since boats like this lack the kind of fuel capacity that is required to be able to motor through lighter winds.
You will want a high quality self-steering vane since its hard to carry adequate fuel/solar panel/battery capacity to operate an electronic autopilot on a boat this small. You may need to increase the water tank capacity and perhaps fuel capacity.
One issue that si specific to boats like yours, is the large fixed portlights in the doghouse. I would suggest that you refit these with heavier lexan (perhaps 5/8" for ports this size). Another big problem with a boat this size is the dinghy issue. You really can'y safely tow a dinghy or carry it on the cabin top, davits, foredeck offshore on a boat this size and even finding space to stow a deflated inflatable and its outboard can be a problem. But having a good dinghy will be critical on a boat this size.
And with all due respect, the most critical element of being able to take a 30 footer around the world is your skill level and knowledge of offshore sailing. It takes years to have the kinds of diverse experience that is required to develop the skills that it takes safely sail a 30 footer around the world and perhaps this is a mistaken assumpstion (and I apologise if it is) if you need to ask us if your boat is suitable, then you probably lack enough experience at this point and so an important preparation will be to spend time developing the various skills necessary.