That style lock, I call them European taper locks, LOL, will definitely hold the wheels they are very strong. We have them on some equipment at my work. Two things, A set of instructions comes with those locks as to how to tighten them, follow it to the letter! Also be certain you devise a means locate the flywheels before you machine away the key way. The weights dont have to be very far out of phase with the crank throw to turn your smooth running engine into a walker.
Next time I have some converted flywheels in the shop I will take some pictures, sorry.