If you can wait a few days, Rick Oliver does a swap service for your shims at £1 a shim - payable to the site for hosting fees ect... Well, He did when I last had some off of him....
The shims are generic - go see any bike shop and they can sort you out.
Unless you have measured the clearances already then you won't know what shims you need and it may be you can swap them betweent he valves and get all sorted out.
I have done three motors now and only bought 5 shims in total. Everything else could be moved and still be in tolerance.