One thing that I did figure out after the engine was back home was that my new Moroso vacuum regulator was stuck open. That was most likely the main reason that I couldn't build much pan vacuum. I had assumed that it worked okay since it was brand new, but that was a bad assumption. I ended up building a little fixture so I could test it and that showed me the problem. So that part went into the trash and I ordered a new regulator from Peterson.

Moroso used to make really good stuff but lately the parts I've gotten from them have been pretty poor. Maybe they're under new management or something.