Is it possible that ones for 42 thru 48 would work? They are not very long, so maybe the length is a problem, but those you can get at pretty much any repo shop, like Mac's, Vintage Ford, Dennis Carpenter, etc.
I made mine on a metal lathe. I used stainless steel bolts and cut them down using the original size for the shoulders. I then polished the stainless steel and didn't have to chrome plate them.