Steve,
The fuel pump ecentric is just acting as a spacer in this application. Not sure why it appears to be worn. There aren't any differences between billet cams for On center and Off center engines. There should be some identification on the back of the cam that could give a clue as the the specs. If you have it out anyway just take it to your local cam vendor and have them run it on the cam doctor and see what the specs are.
Neal