I bought a new set from eBay and they were perfect. That vender is currently out of stock but I found another with a 99.9% rating. search for “2 Rocker Arm Shafts 1941-1962 Chevrolet 216 235 6-cylinder CHEVY NEW PAIR” by seller “old.parts”.
I think either style you have pictured will work. You could even take an earlier one and pinch off the overflow to pressurize the shaft.
