I use this Offy 2x4 intake:
http://www.offyparts.com/product_info.php/cPath/1_6/products_id/195
There's a pic in the link page that can be enlarged. It's actually a pic of the low version. Carb pads are a bit higher on mine.
I was virtually given this manifold when I was buying some used engine parts, and thought the dual system would be a nice touch for my car. It seems to work well, however I don't have an abundance of low end torque. I was thinking of advancing the cam a few degrees to make up for it, but have been advised a manifold change would be a better idea.
There is a few things wrong with this manifold other than low rpm response. To run Holley's, there are adapters required that move the carbs back to make room for the distributor. I have those, but even then, there is not enough room for a large diameter distributor, so I wound up using a Mallory YL (with a few modifications for other reasons), so crossfire potential is higher than with a large dia cap. Ports are tall and narrow compared to most Ford FE cyl heads, so there's a bad mismatch to deal with. So, I may try to find a good dual plane 2x4, if not original, then a good quality copy.
But before I do that, I was wondering if anyone else used this manifold and how they like their low-end response. All comments are appreciated. Thank-you.
ps: actually, the power comes on nicely between 2000 and 2500, and the idle is smooth and good transition off-idle, just not a lot of grunt under 2000 rpm. Makes the car docile down low and no "lurching" or anything difficult to deal with. Runs like a scalded cat once over 2000 rpm or so.