Just 2 cents on Valve Tolerances, Colyncase's post on 4/12 with  valve seats etc.. Have seen other "new  or factory rebuilds" where,  in particular the seats were out of tolerance, mostly in width..  Since valve and guide operation is most critical, I would offer that a check with the specs would be in order before installing the cylinders..  For instance, most all parallel valve Lyc exhaust valve seat dimensions for the 0-290,O-320,O-340,O-360,and the O-540  are 1.7395 to 1.741 inches.  Some of the larger injected engines run a slightly wider seat face..   Perhaps this may not help the present engine life, but NEXT time the engine inspection would shed some light on why a top end was necessary.    A overhaul manual from your engine mfgr lists these and many other dinemsions..   Don Skeele  A&P  320J  235/320