Writing from the navel of Edinburgh...
When I ordered sublimation prints, the image was one sized - so could look a bit odd on different size shirts, or you might not get the whole map. The company I used
www.firelabelbespoke.co.uk/ took the image direct from jpg, so they could print your favourite O-map on the shirt. If you happen to live on your favourite O-map, so much the better ;)