Velocity makes a very nice 27" wheelset, and you can get them made with DT-Swiss spokes and a Shimano hub from various online retailers. To be honest with you, I got a NOS 27" low-end Weinmann wheelset, and it's held up perfectly... a lot better than my old steel wheels. Pairs nicely with the Conti Gatorskins.

It's probably cheaper to convert to 700c, but if you like the look and feel of the bigger wheels, there's no other reason to switch. There are still a lot of tire options, too.