As shown, it's a "plank" head, with no chamber. It has vertical valves like the original, but here the chamber must be created in the piston dome to have quench and turbulence - about $700-800, but you get a wide range of compression ratios.
Since the GMC and stovebolt have swapped intake rocker arms, and both valves are vertical, the stovebolt intake rocker may work for the GMC exhaust (the stovebolt exhaust rocker is definitely wrong, has a steep angle). Stovebolt and GMC rocker shafts same OD but GMC is longer. I don't like the single rocker stand holes, GMC has 2 bolts per stand? Stands may be special. Can't tell if the rockers are left and right offset.
The valve sequence looks stock: X I I X X I I X X I I X, so any GMC cam will work (some heads have different sequence and require custom cam).
Intake will be a problem could begin with some aftermarket manifold for a big 12 port L6 like AMC and slice it into sections.
