There should be a vacuum port in the throttle body to use for the distributor.

If you have no hole in your intake:

For decades, G.M. used a hollow carburetor stud for a vacuum port. These are being reproduced. The stud may be used for wiper vacuum.

Jon

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop