A couple of things to check......63 engines still had the old style cam button retaining plate. Most upgrade to the newer style. Check to see which you have. My 406 was upgraded to the newer style installed and I noticed the same thing that the fuel pump eccentric and sprocket hit the timing cover. Remove the spacer as Jeff advised and put some clay or putty on the end of the fuel pump eccentric and timing sprocket and put the cover on with a few bolts. Then check the clearance to the cover. G.