I like having a vacuum gauge also. Measure vacuum with engine running before you start. It will increase every time you plug a leak.

The parts store sells packages of fittings to connect vacuum lines. Grab a couple of assortment packs along with some vacuum tube of various sizes. One of the most useful is a stepped straight piece that will connect hose sizes from <1/4" to ~ 1/2". Golf tees (plastic) work best for plugging rubber lines.

A shop replaced a friends vacuum pump & wants $700 but hasn't been paid yet. They misdiagnosed a nonperforming vacuum pump when the actual problem was a leaking brake booster. The complaint was that the car wouldn't shut off with the key.

Bottom line: make sure you have isolated the leak before replacing parts.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.