I have been offered a set of secondhand Zipp 400s at a reasonable price. I presume these wheels are a couple of years old and have been superceded by the Zipp 404s? Would these (650c) be suitable for a 220lb cyclist?
Look at the hubs. If they have the old Zipp carbon/graphite looking gray insert in the middle, I’d stay away from them - especially with your size. The old hubs are fragile and really a pain to deal with.
I’d suggest some old specialized/hed 3 type wheels.