In the first pic the vac tree is an emission device that is in series between the vac line from the eng to the dist & blocks vac when coolant temp is above or below a certain point (not quite sure but that's the jist of it). If your state does not require emission devices to be hooked up then just run the vac line from a ported carb nipple to the dist & recurve it starting with the initial. The sender to the left of the tree is the temp sender unit & will have a small wire (purple iirc) with a little L connector thats pushed onto the threads. In the 2nd pic the large nipple is for power brakes & one of the small nipples is for A/C & not sure what the other one is for. If you ain't running power brakes & do not need a vac source for A/C or a vacuum guage or anything else then you can remove it & plug it with a 3/8" NPT plug. 73 was the worst year for discombobulated emission systems. I would check/degree the cam/timing gears/recurve the dist/toss the 73 carb