Aftermarket gauges

Circled part is a manifold vacume tap. It's not sized for power brakes so I assume it is for some part of an emissions system.

Typically the vacume advance is attached to ported vacume port on the carb.

The engine runs beter at idle because manifold vacume is high at idle and advancing the timing 10 to 15 degrees (whatever your vacume advance canister allows)

Oil pressure tap is to the passanger side of the distributer.

There should be a pressure switch in it now ( I little bigger than the water temp sender)

You can get a "T" fitting and some tubing to make a fitting that will let you tap into the oil passage and retain your oil light.