Rocker arms are probably the toughest part of our beloved motors, second only to the oil pump pickup. With respect to the shafts, sealed power and trw both made replacements at one time and they do turn up once in a blue moon on ebay. Edgge has them but god almighty, everything they sell is really expensive. Once you have shafts, you need to deal with the rockers which need to be bushed and sized, adjuster tips replaced, valve end resurfaced. Even if you could put together a set of nos rocker arms, you would still have to size the rockers to the shafts as in just because they are nos does not mean they are right.
The only rebuilding alternative that I know of is rockerarms unlimited. They have been in the biz a long time. I have had a couple of sets of rockers rebuilt by them. They re-chrome and re-machine the shafts, rebuild the rocker arms themselves , then rebuild the rocker assembly. Its a good bot of work but they come back good as new. Not cheap, but worth it in my view. Quiet, stable and working correctly.
http://www.rockerarms.com/
