Which long tube header that is not TTI suck the least?

Whatever you do, DON'T buy Flowtechs.
They hit the power steering box in several places, and #7 tube hits the steering coupler dead on and you will have to shim the motor mounts up at least 1/4''.
And then, they still rub the torsion bars etc. and hang low.
Standard steering would be a lot better............