Rebuilt 350 olds engine ticking noise?

i got a rebuilt 350 and it makes a ticking noise the ticking noise disappears when the car is moving or accelerating but at a stop it ticks. i have no idea what it is i am not losing oil pressure i have great pressure i called a shop to get an idea on what it is i have not gotten a diagnostics yet. they told me it could be a collapsed lifter over the phone but the lifters are brand new and the bearings are new so it can't be a collapsed lifter. the cam is new and the crank is new the engine had all new parts put in except the rocker arms are stock and the push rods are stock everything else is new. i got no clue on what the ticking is and i need a honest answer. i don't want to spend 90 bucks i want a answer first.