It's the other way around, you need a shaft with a tang sticking out to engage the pump shaft. It also needs to fit the bore snugly as the shaft passes through the oil passage.
Haven't tried it myself, but I suspect that because of the way the rear cam bearing meters the oil to the rocker shaft, you might not get oil to the shaft even if there is nothing wrong. My suggestion would be to install the pump drive & distributor, then spin the engine with the starter (plugs out) long enough to build pressure on the gauge. You probably still won't see oil to the rockers at that point, but it will be safe to start the engine and let it idle for a minute or two, to see if that gets oil to the rockers. The flow to the rockers is deliberately quite slow, they basically see no pressure at all even with the engine running.
If not, unfortunately, the most common problem after a rebuild is that the rear cam bearing was installed back-to-front. The 3 holes are not evenly spaced so there is only one way it goes in, and it's easy to overlook the oil hole in the top.
BTW, Welcome to the Asylum