I don't remember all the particulars of how I modified the inner-to-outer (should have got that digital camera sooner), but it did not fit very well at all. I let the pillar & hood hinge area define the outer cowl panel, which fit great, modified the inner to match the pillar/floor/toe/rocker, then after debating whether to just make my own, made the Chevy Duty inner-to-outer fit as best I could. It did require cutting and bending. I still had large gaps and used a lot of seam sealer after the fact. Good thing is that panel never shows and my neoprene wheel well liners keep road salt out of there.
