Can anyone advise on the NPT size and perhaps a part number for a fitting to use for the 440 Edelbrock Performer RPM intake that allows your to draw vacuum from the intake to the brake booster? Thanks!

just looked at my rpm dual plane intake, and it's 3/8" npt, located on #7 runner.
that gives you a fitting size. take that info with you to your local hardware store along with the size hose you will be running to your booster check valve, and select the proper brass barbed fitting that fits both items.
almost every single hardware store or home improvement place has a good selection of brass fittings, one of which will be what you need.
they are cheap too, so if in doubt about what size you need, just pick up a couple of different sizes on the intake thread side. 1/4, 3/8, and 1/2" npt will fit 99.99% of all intakes out there that have a threaded boss for vacuum takeoff.

Nice thing about using brass fittings; brass doesn't grow attached to aluminum or cast iron. That makes them easier to remove if the need ever arises.

Thank you! the 3/8" NPT is what I was believing it was and this confirms it!