I recently picked up a 305 HO from a friend of mine.I wanted to freshen it up by putting in a new cam.My question is,do I have to replace the cam bearings to put in a newer cam? The engine has alot of miles on it.

You dont NEED to replace the cam bearings, but its a damn good idea. Only problem is it takes a special tool to do it, so unless you have that tool and the know-how, it would be best done by a machine shop.