Yep, you have it covered. Sorry for the previous detailed questions. Sometimes members fail to do the most basic of things.

I've got about the same skills you have with it, so, take my suggestions in context:

1) Disconnect the wastegate and see if you can get additional boost without it. It's a longshot, but, easy to test.

2) Apply pressure to the ALDA, directly, using a Mityvac and see if it holds pressure. If it does not, see how fast it loses pressure. If it loses all pressure in less than 2 seconds, then it's possible that you are not getting the enrichment you need from it. Then, the exhaust volume is down and the boost is down.

3) Make sure that the wastegate is fully closing. Any leak at the valve itself will drop the boost for sure.

4) Give the turbo a spin with your hand to see if it is rotating very freely. If it does not want to easily rotate on its own, then the boost will be low because it cannot spin up to sufficient speed.

It's an interesting case. Let us know how you make out.