Checkout my profile to see my Litespeed and front fork swap to the Surly LHT fork. Also the folks at Litespeed are very responsive and helpful (2-3 day turn around).
Link to the Litespeed FAQ about Fork Rake -
http://www.litespeed.com/current/faq.aspx?ac=vw&id=15
You will also need to determine the Axle to Crown distance to match.