The eccentrics normally don't cause problems but one in a 1,000 will have the drive finger break off. I had that happen on a 302.
Normally the pump on the Cleveland is a pain in the butt to install because it wants to be installed with the eccentric on the high part of the cam and places pressure on the lever arm of the pump.
The tension is a little mutch to hold with one hand while tightening the nut.
Be carefull while tightening down. The pump housings are zinc castings and you can break them without much effort.
If you hook up a remote starter switch you can kick the engine a 1/4 turn or so while you are holding pressure to the pump and you will feel the eccentric pumping the lever up and down.
That is how to confirm that the eccentric is good without needlessly taking off the timing chain cover.
The way to take off the timing chain cover on a cleveland you need to lower the oil pan in the front. If the pan has never been off then you don't want to have to do that. If you do then you may as well remove the entire pan and do a new gasket.
Like I said, make sure it is 100% positive that the eccentric is no good before you go to change it.
Good luck and Merry Ho Ho Ho to you all.
