Looking for more zip to my /6 need a little help

Be very careful before you decide to spend any money with Clifford. They have a long and ugly reputation for being a bunch of clowns; see for example here, here, here, here, and here. Much of what they sell is inaccurately described, and a lot of it is not even slightly cost-effective. The good news is that you don't need to go to Clifford to get hot rod parts for slant-6s; there are lots of other, better options. See for example Dutra Duals and header options discussed in this thread and this one, Erson custom cams, HEI ignition upgrade, 1.6-ratio rocker setup from RAS, Mike Jeffreys windage trays, Hurricane intakes, other exotic intakes. Hi-perf engine buildup here, high-perf parts and build info here.