The easiest would probably be the stock system off a 2-ton or larger GMC of the era. I used one off a '59 on my 248 and it has a paper air filter. Earlier '50s ones were oil bath.

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"It's just a phase. He'll grow out of it." Mama, 1964

1956 Chevy 1/2-ton 3100
1953 Chevy 6100 "The Yard dog"
1954 GMC Suburban Now with a new proud owner.