I agree with the recent posts, you can definitely ride the size of bike you have. In the last year I've done long rides on bikes with frames ranging from 55 to 63 cm, and the main difference I've noticed is that my neck gets sorer sooner on a smaller frame. But hey, I'm 49. My neck gets sore no matter what I do. You shouldn't have that problem.

My advice would be to build the bike up and ride it, but don't go overboard. Don't have it powdercoated or anything. Put it up on the "frame don't fit" thread looking for an exact frame swap, looking for a slightly bigger version of the same frame. If you get a bite, go for it; until then, just keep riding.