I always prime with a shaft in the distributor hole and a gauge hooked up right there. I do it several times while rotating the engine 45*-90* each time hoping to line them up at some point. Ideally, it would be best to have someone rotate the engine while you prime it with a drill.
Once it's all assembled and distributor set, you can prime it one more time by removing the spark plugs and spinning the engine over without a load.
