That would work - you would screw a single bmx freewheel in place of the intended cassette freewheel. However, it's a 27" rim, so you're going to have a moderately annoying time finding tires (700c is what modern wheels are). Also, I don't see any info about the hub which is a little weird. Also, you probably want to get a hub that is fixed at least on one side - you can run a freewheel on it, but if you want to go fixed at some point, you're still good with that wheel

If you are in Pittsburgh, Kraynicks on Penn Ave had Weinmann / formula flipflop hubs for $40 a couple of months ago.