Ideally I would be testing the black tubing and connections with vacuum instead of pressure but I am not setup for that. It is fairly easy to test for pressure leaks with soapy water. The lifters are not yet installed and all of intake valves are closed. The entire manifold holds 30 PSI but it leaks out within 20 or 30 seconds. The only bubbles are along the gaskets and not around the black tubing connections. I can also hear air escaping from under the manifold. I don't think I am getting correct seating of gaskets between the manifold and heads. I don't think the gaskets slipped because they were glued to the heads with Right Stuff. I will pull it apart and try to isolate the root cause. I think the gaskets can readily hold 30 PSI when everything is matched up and sealed.
The Felpro 1228 gaskets are $32 a set. The Tim Meyer gaskets are $17.35 a set. I receive five sets tomorrow. Hopefully I don't use them all up figuring this out.