Go to the Surly site (or email and ask if not posted) and check the axle-to-crown and offset measurements. Take these two figures and match them up with any other fork you are considering and it should be good to go.

Surly:
Axle to crown (1"): 368mm
Offset: 38mm

Soma:
Axle to crown (1" threadless measurement): 368
Offset (threaded number): 41mm

The bigger offset will lead to a slightly more active/less stable steering. I would just confirm with Soma regarding the AtC measurement before ordering, since they don't list it for their threaded 1" track fork.