Somebody else may have some leads, but as far as I know, there was never any high performance equipment made for that engine; it was (is) strictly a low rpm - high torque truck engine. You could build a set of headers from scratch, but there is no relation between it and a later model Chevy, or any other v-6. You could also hand build an intake out of sheet metal and tubing. But, if you are looking for performance, why not just swap in a late model crate engine? Much, much easier solution.