do lifters bleed down

Yes,hydraulic lifters will bleed down when you go to set them up because when you`re moving the engine by hand to set up a certain cylinder/valve...other valves are being opened,which puts a load on the lifter and bleeds it down because there`s no oil pressure when the engine is not running to keep it pumped up.

Are you certain that you have each lifter on the base circle of the cam when you are installing them? Proper procedure for installing them below; it's not necessary to have oil in the lifters for the installation.

To install pedestal mount rockers:

1) For each pair (int/exh) be sure you rotate the engine so the lifters are on the base circle of the cam - this is very important. When you install the rockers, both valves must remain closed. Neither lifter can be on any part of the cam lobe - they MUST be on the base circle.
2) Install the rocker and bolt it down to zero lash. Zero lash is reached just when you eliminate the gap between the pushrod and the rocker and the valve stem and the rocker. Tighten with one hand and 'rock' the rocker with the other hand. Just when you reach the point that you can't rock the rocker anymore you're at zero lash.
3) Now - put your torque wrench on it and tighten to 18-20 ft-lbs. while counting the number of turns it takes to reach that torque. It should occur between 1/4 turns and 1 turn. If it takes more than one turn, use a shim to raise the rocker. For each .030" shim you use, you'll reduce the number of turns to torque by about 1/4. If it takes less than 1/4 turn, or you have trouble reaching zero lash even with the bolt torqued all the way to 18-20, then you need longer pushrods.
4) If all goes well on the install, crank it up. If some make noise let the car warm up completely. Then (unfortunately) go back through the install procedure with the components warm. That will usually quiet them down.

Mine has 11 with no shims at all, 4 with one .030" shim, and one with 2 .030" shims. And I had to do the final install with it hot to get them quiet. That approach has them all hitting the required torque within 1/2 to 3/4 turns.

I have a Buddy Rawls custom cam with VERY steep ramp rates, 1.7 roller rockers (pedestal Cobra type), and stock lifters. It runs just about as quiet as it did stock.

Pull all the plugs to make turning over the engine with a socket on the balancer bolt easier. Start with #1. Rotate the motor to the compression stroke - both valves will be closed. Do #1. Then follow the firing order (1-3-7-etc.) -- this will reduce the amount of engine turning you have to do to close the next pair before installing the rockers. Are you certain you understand how to determine if the lifter is on the base circle of the cam?

Extra exhaust gaskets rarely does the trick - sounds like the flange(s) are warped/not true/not flat. When you get the header off put a straight edge on the flange. If it's not true, it's pretty cheap to have a machine shop mill them flat. They'll seal perfectly and bolts backing out usually won't be a problem either.

Crane cams have issues with pushrod lenght, some poeple need longer pushrods, like yours truley.