What happened is someone replaced the timing chain and did not remove the spacer from between the cam and the cam gear and the fuel pump eccentric will hit the cover,if it did not wear through the cover all you will need to do is take the cam gear off and remove the spacer. I did the same with the 390 in my 65 country squire,before installing the motor I installed a timing chain set while it was easy to work on the motor and I read in the instructions about removing the spacer but it did not move when I too the gear off so I thought it did not have one. Well when I fired the motor I noticed a noise so I took it back apart and found the spacer.