Best way to clean Aluminum intake???

[SeattleCarGuy]

Hey guys, I am making great progress correcting incorrect items on my real 4K '67 L78 Camaro. Ordered correct valve covers from Crane, correct carb, clamps, etc.

Question is, what is the best way to clean the intake manifold without removing it from the engine? I don't want to remove it as there are no leaks and it isn't that bad, just wondering if an SOS pad or some other technique would help me clean it while still on engine???

This is a "before" picture. Thanks!