Many hours with Degreaser and a water blaster later, I managed to remove 50 years of old oil and road grime. The reassembly process went smooth, new manifold gaskets, new temp sensor, repainted the fuel rail, and oil service.
The new balance tube has completely changed the engine bay, allowing to remove a bunch of air pump hoses and vacuum lines connected to redundant valves. Absolutely fizzing with how this transformation turned out!