If you are going to be installing the Sprintex SC, the header, ANY header most likely will not fit.
Sprintex is quite clear on this. No clearance at the front of the intake manifold for an aftermarket header. Only the stock or a stock type replacement exhaust manifold will fit under the intake.
I am attempting to save you some grief here. Not to mention the bucks...
On the other hand, if you have decided not to go with FI, then Gibson makes a nice header. But as is the case in with any "bolt in" header, the gains will not be much. What is needed is long tube headers with a 32" primary length. With unequal length primaries, the pulses are not properly timed at the collector to get the best improvement.
Also, I do not like/support the 1 5/8" primary header diameter. For my money, the 1 1/2" is better. IMO, you looses velocity and, again IMO, velocity is what you want in an exhaust system. To get the exhaust as far away from the valve as is possible and as fast as is practical.
Be careful with the choices you make if you go with the Sprintex SC.
I am sure some will argue with me on the primary length but the primaries do determine, to a fair degree, where the HP/Torque peaks will occur. In order to fit this type of header, the entire down pipe would need to be replaced and the exhaust routed in a fashion similar to Wranglers. Under the front of the oil pan which means they would never work on a non-lifted Heep. The whole axle in the way thing...