The a4 I'm doing now, and the conversion I did last, were lucky enough to be older sporters and had their original Redfield Jr. bases on them. All I had to do was find split top rings. I found 2 sets of slit tops, one in 3/4 and another in 7/8. The rings were blued, and the bases had been blued too. An easy fix if I every decide to go original parkerized.
Right now I only have repro scopes. but, with new wood, I don't see the point of springing for original glass.