Ergotec S101GK 1 Inch Threaded Headset

I'm building up a bit of a hybrid, a Bickerton frame up to the headset, where I'm adapting 16"forks and a Dahon style handlebar, stem set up.. the fork stem is about 10mm longer than it should be - I'd like to shorten it, or lengthen the threads by a minimum of 10mm.. can I use spacers to make up the 10mm, or is something more complicated need to be done.. many thanks