The stops arrived from BearingBoys a few minutes ago http://www.bearingboys.co.uk/CABU22Z...ollar_-40280-p
I've tried them in place and they fit without modification! The steering is reduced from near 45deg to 30deg from straight ahead which sounds like success to me. I'll try and learn how to post pictures this evening.
Thanks Flyerncle for the pointer, works a treat.