Pretty simple.
You have a ported vac source on the passenger side near the top of the metering block and a manifold vac source on the base plate.
Use 5/16 inch hose and hook either one up to the vac can.

 

If this is a standard SBC manifold you also have a tapped vacuum port on the back of the intake manifold near the passenger side. Most engines have a vacuum port/tree screwed into that port and it will have 2-3 connections. In some cases the vacuum advance, HVAC, TH350 modulator, and other items are connected into that tree on the back of the manifold instead of the carburetor

Vacuum items you may have
- Distributor vacuum advance - may be a ported (only open when off idle) or unported connection
Full/unported vacuum connections
- Power brakes - usually connected to large port on the carburetor base, using a larger diameter line
- HVAC to vacuum motors for heater/vent controls
- TH350 or other transmission for vacuum modulator
- vacuum valve in air intake
- vacuum valves for various emissions controls

Bruce