A 650c frame will not fit 700c wheels as far as I'm aware. 650 equipment is now harder to come by - though should still find some Velocity Deep V rims in 650c http://www.velocitywheels.com/default.asp?contentID=583

Go with 32 spokes (highest drilling available) good hubs and ask the wheel builder for the most suitable spokes and lacing pattern for your weight.

If the bike is running a Shimano cassette from 8-10 speed this should swap to the new hubs if also Shimano compatible.