What you are looking for is a BMX headset, but the only thing that doesnt match is the crownrace size because those are 26.4 (looked at some tables), thats an easy fix tho.

Probably this one will fit...

http://www.amazon.com/Tioga-Beartrap.../dp/B000C14N4Q

or this ones??

http://www.ebay.com/itm/VP-H755-old-...item2ebb28285e

http://www.ebay.com/itm/Headset-Old-...item4ab667f2c1

ANd the last one... this one comes with a 27 mm crown race...

http://www.ebay.com/itm/1-Threaded-B...item4601b27daa