I have a 67' 427. The problem is that the back side of the cam gear and the front of the block are wiped out causing the cam to walk back and the lifters to collide with the adjacent cam lobes. The motor was recently rebuilt before I got the car. The top end of the motor sure doesn't have much oil laying in it like you would expect. Does the 67 have the oddball rear cam bearing /race groove difference like the earlier 65-66? And could that be the culprit? Any ideas??