You'll need to consider the rake of the replacement fork, along with the axle to crown distance. Also a integrated headset frame has a wider headtube were it meets the fork, so for it to look right, you'll need a fork designed for use with an integrated headset.
Then I would'nt buy a track fork, because it wont be designed to be compliant on the road, and would likely be heavier then you need.
Plus I would'nt buy a TT for almost the same reasons. TT forks are built for aero benefits and stiffness.
Something like this would be better IMHO
http://www.ribblecycles.co.uk/productdetail.asp?productcatalogue=DEDAFORR500
You'll need to consider the rake of the replacement fork, along with the axle to crown distance. Also a integrated headset frame has a wider headtube were it meets the fork, so for it to look right, you'll need a fork designed for use with an integrated headset.