There was a good point in the last post. Since you have a drill press you already had a drill jig. The prop retainer would have done fine as the drill jig.

Your prop has a wood core. Meaning that a wood dowel will be easily compatible with the core material. The method of plugging drilled holes with a wood dowel is one that has been used for a great many years on many propeller sizes and types with little chance of failure when done correctly. Tight fittng and secured with a good adhesive. I do the same in carbon propellers of larger size and have yet to have one come apart when attached to the plane correctly. One of the up sides, if there are any, of using a hardwood dowel is that a dowel with greater wood density than the core of the prop hub will assist in preventing hub compression when affixing the propeller to the engine. Still best to use a torque wrench and not over torque at all, eliminating any chance of hub compression.