In keeping with a long history of poor choices, I kept working on the engine despite the significant amount of other work that needed done to the car. I pulled the intake manifold and cleaned everything up with Gunk, oven cleaner, wire brushes, and the hose.
For anyone keeping score on the poor choices, chalk up another one. I stuffed plastic shopping bags down all the intake ports. Much later I pulled the heads to find rust and other ugliness in cylinder #1. Free tip for everyone–if you’re going to hose down your motor leave the intake manifold on it and be much more serious about keeping water out of it.