If you're stuck for new ones Past Parts Ltd (try google, sorry i dont have their number at home) usually do a great job of reconditioning hydraulics - they have even rebuilt heavily corroded rubbish for me in the past. I can supply you some old ones if you're need old core. On 2nd thoughts I would have thought a glance through a girling cross-reference book would yield what other vehicles they were fitted to which may be more readily supported by specialists.
eg I have a 64 Galaxie - cost of starter from specialist £209, cost of same starter for JCB (of all things!) from JCB dealer £124. I only found it was the same by looking at the Lucas book and found the Lucas number the same although the Galaxie & JCB numbers are`different.
Cheers
Jules
RatSport www.ratsport.co.uk