I recently tore down my 1957 312 to do an overhaul which is the first time I've been into a Y block since 1964.  I'm now ready to start reassembling the engine but after studying the exploded view in my 1956 factory service manual of the timing chain and related parts I noticed the timing chain lubrication trough was missing along with what is described as a counterweight that mounts behind the fuel pump eccentric on the end of the cam.  For proper lubrication I would guess it's pretty essential to have the timing chain lubrication trough even if I have to fabricate one.  What I do not remember ever seeing before is the counterweight that mounts behind the eccentric.  This part was missing in my engine.  Is this an essential part that I'm going to need before going any farther?    

buddy