Lovely old piece there Boryx!
You certainly have a real gem there mate, all that waiting you did certainly paid off!

I was thinking the same as Huvius, but with reduced Nitro for Black loads then it won't stress this old lady too much!
You might be lucky, someone here may have already done the NFB loads for this calibre.
Please keep us all informed on how you go, it's a rather interesting calibre!