Alright, I can see your kick down linkage for your auto. And is see that there is no AC and no power brakes just like mine. Nice valve cover there.
I'll put up some HEI and electric fan pics later.
For the carbs, your factory carb looks similar to mine, but there are some odd differences. I can't see where the lines for the EGR and EVAP (charcoal) canister are going or coming from. Could you get a pic of the front of the engine and over the EVAP canister so I can figure out how your hoses are running? Alright I got a few more pics of my carb:
First here's a pic of my air cleaner and a lot of other things off so you can see how everything routes. I have the factory assembly manual, so I have checked all the attachments to make sure they are correct. I'm putting it on top so it is right below your engine pic in the message above so you can see them both.
I don't have pic of the front of my carb, but here is the passenger side of it. You can see the solenoid is there like yours, but I have an electric choke there and you have a hose going somewhere? You also have what I guess is the timed vacuum port on this side, which should be running to both the EGR and EVAP (charcoal) canister? It's hard to see, but it looks like you have the main EVAP hose and PCV hose running to a vacuum port on the manifold in the same place as mine.
Here's the rear of my carb. Aside from the lack of an electric choke on yours, it looks the same to me. The EFE vacuum line appears to connect to a port at the base of your Monojet, while on mine there is a vacuum port on the manifold for it.
Ok, here is a shot of the driver side of my carb. Right away on the upper top right you see a port that is not on yours. This is a timed vacuum port and it runs to a thermal valve on the water neck which then runs to the EGR and EVAP. On the upper left side is a hose on mine that vents the fuel bowl to the EVAP to prevent fuel vapor in the bowl from being released to the atmosphere. On your's someone has capped it.....which there really is no reason to as this just passively collects fuel vapor from the carb when parked and keeps it from smelling up your garage. The Holly 390cfm has bowl vents that just vent straight up so this hose is useless once you switch (although you could drill a hole in the bottom of the air cleaner and get a port to seal it too and hook the hose to try to collect any vapor settling on the bottom of the air cleaner).
On the top of the pic you see the bottom of my air cleaner and the hose running from there to full vacuum port at the base of the carb in a tee fitting with the vac adv line too. I suspect this is where your dangling air cleaner vac line plugged in too, but someone broke that part of the tee off and pushed the vac adv hose all the way on to cover the hole. Pull it off and see if there is a broken off port tee there.
Here is a labeled pic of how the hoses function. It's hard to see the lines running from the PCV and EVAP to the manifold port which has a tee fitting as well.
And here is the 1978 49-state diagram of how everything runs. I made notes on for a Holley-390/Offy/Stovebolt swap as to which hoses can be retain and what they will plug into, and which need to be deleted.
Here's my labels where the hoses go on the Holley 390cfm for the swap.
Here's one more shot to show how the '78 is set up. You can see two thermal valves screwed into the water neck. One on top is attached to a delay valve in the line running from the distributor vacuum advance to the full vacuum port on the bottom of the Monojet.
The second one is on the bottom half of the neck and has one line running from it to the vacuum source on the carb which is the top timed vacuum port. The other line runs a few inches and then has a red plastic Y to split the line with one going to the EGR. The other line goes to the EVAP canister where there it plugs into one of the two valves on top of it (I forget which one, need to snap a pic of that).
I hope that helps. Take some pics of the front of your engine and the EVAP (charcoal) canister and I can see how your hoses are routed, because they are not quite the same as mine.
