Glen,
I hope you make your trip, sounds terrific. I have always found SPAX prompt and helpful. I would contact them direct and explain your situation:
sales@spaxperformance.com
By the bye just to clarify Spax can supply dampers for the Ace which limit droop or rebound and I think this is essential. The original design of Armstrong dampers did not limit travel with the result that at the rear the drive shafts exceeded their limit of Hook joint angularity and at the front allowed suspension travel to be arrested when steering track rods fouled the wishbone mounts. The two letter suffix identifies these reduced travel dampers on the part numbers:
Front G9442AS
Rear G623EA
I believe SPAX will still supply their original part numbers which must have been copied from the original Armstrong dampers. Personally I think allowing the unrestrained suspension excessive droop probably accounts for some of the cracks we see in older chassis and bodies and I would not use them.....
Barrie