Well, increased it up to where I was looking at 10px per mile, about 8000 wide and 4000 down. Fireworks screamed in pain and died having maxed it's 32 bit paging file out at 3.76 GB handling the file. I switched to Photoshop to get it to that size and Wilbur took it happily.

It's going to be a long redraw though, but this world is very old and very overdue for new maps.