The Ford Master Parts Catalog list both oil bath and dry type air cleaner available in 1966 for 6cyl and V-8 Broncos.
Does this look correct? The family I bought it from didn't really do any mods to it. Not the best pic but the air cleaner sure looks original to the engine.
Your air cleaner looks very close to the one illustrated in the Ford Master Parts Catalog.
Your master cylinder is not correct, should be a single reservoir on a 66.
Even a 66 built in 65 will have C6 part numbers.
Maybe the oil bath setup was optional?