64 Dart 273 Engine Vacuum

CAVEAT!!!! Don't rely on parts store vacuum gauges, the typical fuel pressure/ vacuum gauge

Not long ago, I put an AC system into my neighbor's son's house, this is R410A, and I read that they are way more finicky on vacuum, so I ended up with a new pump, some additional test equipment, a nice big 3" gauge, and 4 old automotive gauges I've had for years

NOT ONE of those old automotive ones (along with some of my other stuff) was anywhere near correct. I believe they were off 2-3" Hg in some cases