you can easily get a 27'' track wheelset on ebay. they are always up for grabs. here is a decent pair:
http://cgi.ebay.com/TRACK-FIXED-GEAR...QQcmdZViewItem
but again, 700c would be better, even if you had to get a new brake (i didn't have to). then you must choose a gear and purchase the appropriate cog and/or freewheel and chainring (if necessary) and shorten the chain. then you need a lockring, rim tape, tubes and tires. you are ready to ride. i did this with no problems, but there are people on these forums that will tell horror stories about conversions. i guess it's different for everybody. i say just dive right in!