I know others with a lot more knowledge than me can tell what has worked but if it were me I would use a Clifford stlye manifold over the Offenhauser style. I like "tapered" intakes runners. When the valve opens the velocity at the valve is greater and it doesn't have such a "square" corner to go around. As for fitting you application?
The other thing I would do is use a progressive 2 barrel. Much better on economy. On any street aluminum manifold make sure you heat it for the best driveability. Personally I like exhaust heat as the stock exhause manifold does. Good Luck I'm sure you will hear from others.
