The Zinc Chromate used by the U.S. aircraft industry during WW2 was generally in two colours, Green Zinc Chromate, and Yellow Zinc Chromate. The Yellow had a hint of green to it, and looked like a dirty yellow, with a slight metallic look, whereas the Green had a very slight hint of yellow, and looked like flat mid green.
However, the B26 Marauder was finished internally in Interior Green, which, for want of a better description, was a semi-matt 'apple green' shade. This paint was used in the rear fuselage, the cockpit, nose compartment and main bomb bay, with fittings, such as seats, often being in a slightly darker shade, known as Bronze Green, with dull yellow cushions. The radio room and the rear bomb bay were in clear laqured aluminium, which, in 1/72nd scale, would be painted dull silver, although these areas will not be visible on your model. The nose gear bay was also this colour, whereas the main gear bays were zinc chromate, green.
if you go to the web site of the National Museum of the Air Force (was United States Air Force Museum), and look under 'Cockpits', you will find some fairly good pictures of the cockpit, bomb bay, mid section and waist gun area of a B26, which shows the Interior Green colour.
I hope this helps a bit.