I'm pretty sure you can get an answer from Red at Redax Engineering in Brissy. He's built a couple of Scorch framed Lavs that are competing in post classic racing. These bikes are riddled with nice touches and careful detail. Give him a call and if he doesn't have any I'm sure he'll know where to get them.
Replacements were definitely available, but I don't know if they still are. Possible ItalSpares at the Happy Farm may have them, or alternatively, it may be cheaper to get your discs ground to remove the chrome.