273ci header question

I would try the spitfires. Have them on my 66 barracuda they do fit tight but they work excellent. Although I had to fab my collectors they dumped right on top of my torsion bars other than that run 2 1/2 pipe out back with some good mufflers your set.btw I did try the TTI ones lets just say very difficult install. They are on my garage wall waiting for my 340 6barrel build.