Will be very tough to get a replica stock made due to the heel drop of those older guns. But unfinished stocks that have a custom look and actually improved lines can be inletted rather easily. I'm pretty sure Richards will inlet the Old Classic Sporter for the M54, but you will need someone to fit, checker and finish it. Won't be cheap!
Sherry Abraham in Oregon is one of the best and very reasonable in price! Try a Bing search for "Sherry Abraham"+"Custom Checkering" and I think it will pop right up.