You said the the engine has been rebuilt. The heads if they have had a valve job, more than likely the heads have been surfaced and many shops when they bore an engine they will surface the deck. there is really no way of knowing from the computer what is going on with your application but maybe a few pictures of it apart and of the parts you are using could shed some light. or find the local MoPar guy and pick his brain or pay him to look at it.