305 header size ???

[Billy Nees]

Ya know, you don't post with a real name so I can't tell if you're a Newbie or a veteran of Stock. If this is your first build, then good luck picking the "correct ones" the first time around. Heads, intakes, carbs and cams change over time and that will change the working range of this combo. Unless this is a "top shelf, best of everything" build by a known builder, who knows the combo, then I would stay away from a tri-y header to begin with.