Change the coolant barb to a single upright for the heater hose connection. The OEM barb with the outlet to the carb is tough to remove. I would consider removing the intake manifold and flushing it out. Chunks of iron from the block can settle in the coolant plenum under the base of the carb and it leads to electrolysis. This is a known common problem that causes the underside cover plate to develop pin hole coolant leaks. They can be repaired but it requires the base plate to be carefully ground out and a new plate welded in.

*tip - drain some coolant before removing the carb. If you forget to do it, coolant will backlog into the intake manifold and make a mess + potentially make it's way into an open inlet valve.