What are these intake holes for?

1-2 & 7 are water holes. There rear one gets plugged, 1 or 2 get used for the heater core, plug the other.
3 is the temp sender
4 is for power brake vacuum, cam be plugged or you have the power brakes connected to the carb.
5 & 6 are for mounting the coil bracket. These are level for the after market bracket. The factory bracket will work.

If you wanted to run a temp sensor, then the drivers rear water port might be of use.