I don't see why not, however, be sure that they are good quality hard ones. I've had a number come to me in recent years after the shaft has been replaced and the owners also replacing the split pins (as you would), only to have the poor quality split pins shear. In one case the guys couldn't find decent split pins and so he fitted roll pins.
If the R clip (or what ever) shears, there is a possibility that the rocker could break, or in extreme circumstances, the rocker depress the top spring retainer, allowing the valve keepers to escape, it would be seriously game over then.
If you are going to do it, check what would happen if the R clip did shear.