the one right behind carb is for an automatic tranny modulator. I have a T screwed into that and leads to tranny.
Some of those little one are for accelerator cable brackets/kickdown cable bracket, etc.
It looks as though you have two distributor hold down clamp holes...never seen that before.
I am sure one near the thermostadt is for a Thermal Vacuum Switch that would control certain emissions stuff, if you have them. One of those if for the heater hose attachment.
This may blow your mind, but, I created a website years ago when I removed my old 350 to put in a 383....many pics that shows routing of thousands of vacuum lines. This may give some idea about some of the intake holes...
http://www.delbridge.net/vacuum.html