Sure almost everyone sells a block hugger.
The tubes have to be a linear distance of nine inches from port to end of tube (inside the collector) to totally segregate the exhaust pulses from adjacent cylinders. That is the only benefit a header in a closed exhaust system offers. If you where running un-capped, and had headers with a primary tube tuned to the length that delivers an exhaust pulse at the collector at the RPM where the motor makes peak torque you also gain a scavenging affect that sucks the cylinder clean of exhaust gasses. This is the advantage of long tube headers over short tube. However only competition headers (large diameter primary tubes that are equal in length so that they take up a lot of room under the hood) offer this advantage and because they have no collector flange; they are never used capped up which is hard to drive on the street without attracting police attention.
Some headers are imitations of a "Ram's Horn" cast iron manifold with two center pipes shorter than the ends. This style is basically just a cast iron exhaust manifold replacement that offers no performance advantage. Others have equal length tubes and are offered with an Oxygen sensor and AIR injection ports because they where designed for late model Camaro's with EFI. Because there is more room under the hood with an Impala this side of a truck the header companies all build headers to fit the tightest space restrictions (the Camaro or Nova). This is why they list the exact same part number that fits your Impala under Chevelle, Camaro, and the Nova. If it will fit where there is no room they will fit where there is lots of room , BUT they will have issues with plug replacement, especially if you have angled plugs.
If you have excess cash burning a hole in your pocket then the ideal solution is a set of Sanderson cast iron headers. They look like a set of block huggers that look good, and they have no issue with rusting out, or leaking. Polished and hard chromed or even aluminized coated they will add to the bling under the hood.