You might want to try HeartThrob Exhaust. I ordered their kit for my 82 C10 through one of their distributors for a very low price, a little over $200 shipped as I recall. Pipes are 2-1/4" mandrel bent with a choice of tailpipe exit -- sides or straight back. I specified their stock replacement mufflers, which sounded weird, so ended up replacing them with Walker Dynomax Super Turbos.
http://www.heartthrobexhaust.com/
Call them. They are very helpful. I actually spoke with the guy who said he'd be the person bending the pipes for my kit.
Please know that a header back kit will probably need some mods, because all headers are different.
Edit: I think the dealer I bought from was Auto Accessories Garage. They had a new customer discount and free shipping, although the kit shipped directly from HeartThrob.