Why are the cam base circles off? I have always known if you bought a cam for a certain engine all the stock stuff bolted up. Big block mopars are not adjustable and you ordered a big block cam and never had to think the pushrod may be different. Coming from fox body small block ford stuff, we ordered a cam for it and never worried about the pushrod length being different. Ford makes bigger cams and so do others but never heard it was an issue. The factory pedestal rockers are non adjustable. Once you changed heads and went with stud mount I guess if there was a slight difference you wouldn't know being you adjusted them when you bolted them on