This is the IPMS information that I used for my -G. This is taken directly from their site.
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Boeing B-17 Flying Fortress
Early B-17s had overall Zinc Chromate Yellow interiors, Bronze Green cockpits and navigator's stations, and Aluminium lacquer bomb bays.
For F and G model B-17s, the general rule for "control cabins" is Bronze Green. Instructions identify the "control cabin" as the nose section containing the bombardier and navigator, the cockpit including the pilots and top gunner/engineer, and the radio room. Later official specifications for the B-17F revised in August 1944 called for Dull Dark Green in the same areas. Some Douglas-produced B-17Fs possibly had Interior Green control cabins.
The same 1944 document calls for use of Bronze Green on exterior anti-glare panels of uncamouflaged aircraft. It remains controversial if this instruction was ever followed in B-17 production, most colour photos of the B-17s showing Olive Drab anti-glare.
Inner fuselage sides in the nose, cockpit and radio room were covered with green canvas padding. The cabin floor was made of varnished plywood. In high-traffic areas, floors were covered with black rubber mats anti-skid purposes - in the waist, the radio room and the top turret area. The floor in the pilot/navigator cabin was left in natural metal. Pilot and navigator seats were most probably Bronze Green.
Aft of the radio room, the fuselage interiors of many early-production B-17s were painted Zinc Chromate Yellow. Later versions of the aircraft, camouflaged as well as natural metal were often left in bare metal with Zinc Chromate Yellow or Zinc Chromate Green bulkheads and longerons. Note that the waist-gun areas were also left in bare metal, presumably because there were no glare problems for the gunners there.
Rear fuselage of the B-17F at the Long Beach assembly line showing the area near waist gun stations. This photo provides a prime example of bare metal interior with Zinc Chromate Green longerons. Some of the bulkheads further aft are also green, while those closer to the photographer are left in natural metal.
The prevailing colour inside gun turrets seems to have been Dull Dark Green, on later models also flat black.
Among the areas left unpainted were also bomb bays and bomb bay doors, although some sources state Neutral Grey for camouflaged aircraft.
Wheel wells are believed to be usually painted Interior Green.
Another photo of a tail of a camouflaged B-17F Flying Fortress at the Douglas factory in Long Beach. The fuselage construction illuminated by flash behind the workes' heads shows that there were at least two different colours of primer used. Another mystery.
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You can find more information here:
http://www.ipmsstockholm.org/magazine/2004/01/stuff_eng_interior_colours_us.htm
I mixed my own color for the interior of my -G using Model Masters Acrylics. Green zinc chromate and gloss black in a 12:1 ratio. It yeilds a nice green that very closely represents many of the photos of both restored and unrestored -G's that I could find. I hope this helps.
BK