Last time I checked Sarco did not have "C" stocks.
If you want a new stock your best bet is a CMPicon stock, they are of excellent quality and the customer service is second to none.
The required fitting of the CMP stock took all of an hour and some sand paper. Staining and Tung oiling is what takes time since the different applications have to be allowed to dry...
I'm pretty sure you will have to do the same to any new stock you purchase.

Have you checked Dean's Gun Restorations site?
http://dgrguns.com/New-03-or-03A3-Main-Stocks.htm
http://dgrguns.com/New-03-or-03a3-Stocks.htm

D.