There were originally three paths for water to go through the flat top carb system.

1) First was through the carb bodies themselves. Those have already been removed since you are now running round top carbs.

2) The second path is through the intake manifolds. Inlet you have labeled #1 and outlet labeled #2. Since they are disconnected from any water source, you can plug them, remove them and plug the resultant holes, or simply leave hang open.

3) The third path for coolant is routed through the balance tube. Inlet comes up from underneath the two carbs about in the middle. It's the flare style nipple at the bottom of this pic:

and the outlet is what you have labeled #3. That outlet pipe #3 is rotated 180 degrees from where it's supposed to go. It's supposed to go around the back of the head and tie back into the water pump inlet.

The other thing in the pic above (#5) is your original idle speed control. Again, since you have switched to round top carbs, that thing doesn't do anything anymore (assuming you have it tightened down completely). You can plug, remove and plug or leave it as is.

@Captain Obvious That’s great info! Tks for the feedback.

From your post I understand that I should have changed the balance tube when I removed the flat tops (that will be kept for future use) and changed to round top’s. 

I will clean it up a bit more the area and plug those holes. 

One step closer to turn the key get that car back on the road and finally drive it to... the storage unit for winter!...??

LOL. Well if you ask me, the problem isn't the balance tube. The problem is that you removed the flat tops.  

Good luck with the project. Too bad you won't get to enjoy it much this season.

@Captain Obvious The flat tops will be back on, nice and clean some day... They are stored in my “secret layer” waiting for some will to go true them,  but not now, as I just want to finish the ‘73 and get it rolling on it’s own power at one point... ??

Haha!! Fair enough. Hope it comes together!