Here is what I have gathered, this is just from having a few of these trucks, parting out a few & a bunch of factory literature I keep near the toilet for reading material
1. In 66 the dash from door to door was the darker charcoal fawn color, everything else is 22151 med fawn poly, dunno about the plain "fawn"-I have wondered, maybe it was used on Corvairs or Step-Vans
2. some 64's had the column white, but 65 & 66 were fawn-on some trucks the fawn looks more silver than brown, I guess this is due to variances in mix+it being metallic(toward the bottom of the paint gun/can it might get more silvery)
3. the band was ivory, in 64 & 65 the whole inset was ivory
4.The 327 in 64-66 was green from the factory on the original trucks i have seen.
Of course 40 yrs have passed, all plants did things differently, they were mass produced work trucks & I may be crazy so nothing is set in stone.