Since i have all my new vaccuum pump stuff ready to install where is the best place to plumb up for a gauge.

I have one to put in the dash on the car so i will be running a line back to where ever i tap into.

I just ran the gauge line to the back of the valve
cover

Fuel pump block-off plate...........

I use a fitting in the top of the valve cover, near the front of the motor, thinking oil might find its way to the back under acceleration. Purely theoretical.

Just make sure if you plumb it into one of the valvecovers and put the vacuum pump pick up in a valvecover that you put them ini opposite covers. IE inlet on pass cover, gauge tap on Dr side. That way you will ensure you are making vacuum in the crankcase not just that cover

I woudl also recommend you put it on the inside edge of the valvecover as a pickup point. A B1 leaves a fair amouont of oil up top, if you try the front it will suck oil on decel. Here is where mine is. Hard to see but I used the Star fitting and it is on the drivers side cover.