Fuel System: Carter WCFB model differences?

[riversidevw]

I've been looking for a decent rebuildable WCFB core for the '58 President. The original was the late-production version, the 2575S. So far a 2214 core has turned up, guess the 2214SB was the predecessor in late '57 through early '58. Parts book lists different repair kits for the 2214 family of carbs and the 2574S/22575S '58 carburetors.

Any real differences between the 2214 and 2757S? Are they completely interchangeable?

Thanks.