I have the tarted-up chrome crown version on my Stanyan, nice solid fork (and frame).

Mine is 1 1/8" and threadless, Soma does have a threaded "track" fork for 1" threaded which is the spec on your GS.
Brake reach, rake etc. best taken up w/ the folk at Soma.

http://www.somafab.com/archives/prod...ded-track-fork

Fork failure is not something to mess about with, a very thorough examination is in order for your Raleigh.
Replace if in any doubt.

-Bandera