Ross, CZ USA has Pre B style spur hammers. I bought one last year and put it on my project Compact a few weeks back.http://shop.cz-usa.com/ProductDetail/0420020011_Spur-Hammer-Pre-B-75
Took some stoning to make the new safety work with the original sear and the new hammer. I ordered an adjustable sear from Cajun Gun Works but didn't wait for it (I'm impatient) and stoned the safety to get it to work with the amount of movement the new hammer allowed the sear.
On a positive note, the new spur hammer gave my Compact a 3 lb. SA trigger pull with absolutely no polishing of any of the internal parts/pieces.
Oh, you'll want that special hardened starter punch, too. Need to get that pin moving to get it out of the hammer. I reused the other parts after I got them off the ring hammer that came on the Compact.