Prob too early for OSAC.
Maybe its the decel advance. No harm with using that. it gets both ported and manifold vacuum and then connects to vac advance.
Evolution of the Cleaner Air System (Session 287) from the Master Technician's Service Conference
The only one I can think of off hand that might be important to use connect would be one that also operates the EGR. If there is EGR. Which on a rebuilt engine, maybe. maybe not. '72 Calif only AFAIK
