The 350 Holley 2-barrel should be an interesting stepping stone between the original Rochester 1-barrel and either the 390 Holley 4-barrel or the 400 Carter 4-barrel.
Remember 1 and 2 barrel carbs are rated differently; so comparing the 350 to 390 or 400 is comparing apples and oranges.
The original 292 single barrel Rochester was rated 250 CFM on the 1 and 2 barrel scale.
Converting the 250 (original) and the 350 (Holley 2 barrel) to the 4-barrel scale results in:
Original Rochester 1 barrel - 176
Holley 350 2 barrel - 247
Holley 390 4 barrel - 390
Carter 400 4 barrel - 400
Is your Offy an open plenum, or does it have 4 holes for a 4-barrel?
Jon.
