I doubt that you'll find a carbon road fork long enough to reach around 27" wheels. A cyclocross fork might work, though.

Steel forks with threaded steerers are available, and you're more likely to find one that can fit a 27" rim with a fairly narrow tire. To determine threaded steerer length, add 4-5 cm to the length of your head tube, depending on the stack height of your headset. Check this search forks.
http://sporting-goods.shop.ebay.com/...&_osacat=42318