349 CI on the cheap
You can bolt anythign on a 4" arm engine, but you are right. The heads and intake begin to choke them very quickly. Meanign low rpm. But the 3.58 arm is a 360 base. They are fed fine with std heads, assuming the combos are properly built. 318 and 340s are very similar. 360s are able to be cammed and headed a little differently. If you dont, you get a power band that tapers off earlier than what might be expected.