When I rebuilt my motor I decided to delete "potential" problems. I'm a Murphy's Law believer and over my lifetime that has proved beneficial for me at least. You know what us poor people say "more money, more problems". More things that can fail. Break, leak etc. so if I don't need it it gets gone. It's hot down here plus my 240 lives in a warm garage so after reading a lot of threads I decided to do away with the extra heat. The thermostats go bad and the coolant flows through the carbs all the time, at least on the set-ups I have owned.
I talked to Bruce at Ztherapy beforehand and he said just use NPT brass plugs in the soft aluminum. They would make their own threads, no need to tap the holes.
I did the thermostat housing and the rear carb's intake. I left the pipe in between the intakes though. That rascal wouldn't budge when I tried to turn it out and I didn't force it so it still looks good and isn't all bent up.
I plugged the red circles and removed the hardline behind the cylinder head. My car runs great and my carbs get cold to the touch in the winter, they are cool to the touch even in the middle of summer. I'm now race car mechanic but I'm very familiar with nitrous and know the cooler the fuel the better a motor will preform. Like I said it hot down here.