Tradd, I think from researching yesterday that it is a 3/4. I agree that a double mattress is the one I will try. I want to try to get a totally foam one, no intersprings, and cut it with a knife where it is too long and too wide. Or maybe I can just smush it in to make it fit. I was going to build a platform on top of the side rails that would fit a full perfectly, but it was going to look too clunky, and part of the charm of the bed is the siderails, which are higher at the ends than in the middle.
It's a real pretty Eastlake bed that I got at a terrific yard sale out in Lake Leelanau, right down the street where we rented a farmhouse for our family reunion. It was 20 dollars and covered with old yucky paint and mildew, and I worked hard for a year to try to strip it but it was so difficult I ended up painting it a really cool color, Lunar Tide, so it's like a piece of green cheese from the Moon. It has a tall headboard and smaller footboard and I hae never had a chance to use it, and I'm excited about getting it up and running.