For a P-51B use Interior Green ANA 611/FS#34151 in the cockpit and wheel wells. Although some photos show do yellow zinc chromate in the wheel wells.
Oh yes, later P-51 cockpits had a plywood floor. Many modelers depict this as bare wood. This is incorrect, per the P-51 erection manual (the instructions to build a 1/1 scale bird) the floor was coated with non skid paint, flat black with sand in it, the same stuff as used on wing root walkways. Just in case you hear somebody talking about the plywood floor of a Mustang cockpit.
F is for FIRE, That burns down the whole town!
U is for URANIUM... BOMBS!
N is for NO SURVIVORS...
- Plankton
LSM