340 headers?
there are no headers on the market that fit worth a damn but TTI. even the hooker super comps hang low, snake around the steering box poorly. even the header flange at the head is not that thick. yeah TTI's are expensive, but the mandrel bends, around the steering box, and the tucked to chassis fit is well worth it. most headers will have to be replaced in a few years. my buddy has had his for 5-6 years driving it in the rain and all and they show a bit of rust, but they still work just like day 1.
I would probably throw manifolds back on.