You can buy a set of wheels from BWW:
http://www.bicyclewheelwarehouse.com...ewCat&catId=45
Then get a cheapie BMX freewheel from ebay or wherever:
http://cgi.ebay.com/Shimano-Freewhee...item53e26c8c39
Take off derailleurs, pick which front chainring you prefer, shorten chain so it fits, youi're done.
Your rear dropouts are almost definitely going to be wider than the 120mm rear hub on the wheelset, but it's old steel so just crank down on those bolts and crush the frame. No biggie.