650c is still a fairly common rim size. i know mavic and velocity both make a few 650c versions of their other clinchers. i think you should leave the frame and fork as it is, and have a new 650c clincher rim laced up to your existing hub. 650c clincher tires aren't that big of a pain to find either... front wheels are the easiest to build, so this could also be your first wheel build... or you can also always check ebay for a used front wheel as well. consider yourself lucky you don't have one of the weirder sized pursuit/tt front wheels.

putting a taller fork on that frame will slack the headtube angle out too much, aside from how weird it would look, i think it's a bad idea...