hi Richard,
I wasn't aware of a Olive Drab from the BSC 381 1930 chart . Mike Starmer doesn't mention it anywhere in his writings . For colour selection , I always try to find a sample of the factory paint under clamps and brackets . I have found Mike Starmers work to be very good , the Light bronze green 22 AKA G5 found on my CS8's , matched perfectly with his recommended Humbrol equivalent .
Mike