Your turbo30 transmission requires full manifold vacuum to it's vacuum modulator on the back of the transmission. It usually has a solid metal tube running up to the intake and run off of a tee from a fitting on the back of the intake manifold. That tee sometimes feeds the heater control and the power brakes.
The 2 ports on the front of the edelbrock carb are for the vac advance to the distributor. Depending on which distributor you have--some HEI distributors prefer running off timed vacuum which would be the port with no vacuum at idle. For other HEIs and the original stock ignition system you need to run off of full manifold vacuum which will be sucking pretty hard at idle. Just be sure there are no leaks.
