I may have missed some posts but I didn't see any reference to having the rocker shaft on correctly. If it not installed correctly you will have lots of rocker noise. Make sure that the notches on the shaft is down and toward the front on the drivers side and down and to the rear on the passenger side of the engine. If this is not followed there will be a lack of oil to the top end. It is also possible that all the lifters did not pump up and that shutting the engine back down and restarting will allow them to purge air out of them and to pump up.