Edelbrock Carb Question- Vacuum port

Hi all,
I have a 1406 edelbrock 4 barrel carb, and there are 2 small ports on the front. Ive had the left one in use for years, but my 1978 engine with pcv and breather only- no emissions items installed, makes me believe I should switch the port and plug the opposite side. The non plugged one runs to my distributor vacuum.

The left one is labeled as (from edelbrock manual):
3/16” TIMED VACUUM
(Distributor vacuum advance port
for emissions controlled engines)

The right one is labeled as:

3/16” MANIFOLD VACUUM
(Distributor vacuum advance port for
non-emissions controlled engines)

Anyone have an idea which I should be using?