my autoshop teacher said if your truck makes noise like that when you start it you need to turn up the radio for a second to drown it out. He said it just takes a second for the oil to get up into the valvetrain--more noticable with hydraulic valve trains.  But on your firebreathing solid cam set up, it is also normal to take a second for the oil to get up top.  Don't rev your engine to make it happen faster--that just grinds stuff together more.  Stick a long screwdriver onto the valve cover to see which valves are making the most noise and put the other end to your ear--redneck stethoscope.  You can also see if your timing chain is making noise this way too--just don't wear a tie when you do it :     Umm, oh yeah, lest your forget: A tappy motor is a happy motor.    This is still my favorite icon.
cheers