They may be small enough to choke the stacks. Each suction pulse is an entire cylinder drawn very quickly through a small tube, without that huge buffer of the manifold plenum. I'm guessing: the stacks and throttle discs are about 1-3/4"? Because the pairs are so close together you may find that making a base to accept 2 stacks with a single filter works better, 3" wide and 6" long, as tall as possible.
For all of you salivating over the head, it fits a 216 (or 1941-52 235) just fine, but it's 15 bolt - won't fit the 18 bolt 1953-* 235/261.
