I have replaced the intake on my 390 fe engine which requires the removal of the valve covers rail and rods. Everything went nicely all of the rods are seated correctly and I torqued the four bold down in sequence up to the proper torque specs of 45 foot pounds. After getting everything together and timing the engine I started it and heard a loud noise that sounded like noisy lifters but it is so loud it is almost louder than the engine noise (it is straight pipped very loud). I did an oil change before I started it and it has never been low on oil I always keep up on maintenance. I also got me aluminum valve covers for it as well.

 

Welcome to the site..
The pushrods can sometimes be different lengths, more so on rebuilt engines. When removing the rocker shafts, the push rods should be location matched, and top/bottom orientation as well. Sometimes when tightening the rockers shafts too quick, and a lifter/s have oil expanded, it can drive a valve into the top of piston, depending on the pistons.
With the covers off, manually roll the engine over to take the cams pressure off the bottom of the/each lifter. With your fingers you should be able to spin the push rods. If any of the pushrods are bent, it’ll show up fairly easy. Sometimes manifolds depending on who’s, won’t have enough bore clearance for the pushrods..
You could always run the engine with the covers off and check for shaft/rocker oil delivery

 

so at tdc I measure from the top of the rod to the lifter and they should all be the same distance away?