I have tried both, the tapered and squared off. I did switch to a roller cam and I am hearing that there is a difference in the shaft/gear on the roller cams. Checking into that now
I have the oil pump off, in fact, I pulled the whole engine back out because I wanted to check the oil passages just for the reason you are saying. Rocket had some good advice that i had not thought of, the length of the shaft and the distance between the distributor and the slot that it rides...