It's a convertible (torque boxes) something most people have never seen on a pre 1966 car.
There is no specific paint code for Race Hemi Orange than I'm aware of but Frank Badelson sells a correct shade of orange for your engine. It is a much paler pumpkin orange as compared to the reddish orange of Street Hemi Orange.
Race Hemi Orange:
1962-64 413/426 Max Wedge
1965, 1967, 1968 Race Hemi
1966-1968 Street Hemi (and possible some early 69's)
Street Hemi Orange:
1969-1971 Street Hemi
Frank has a few color matches he's done off of original engines he's had, he came up with 3 shades, Race Hemi Orange, "Early" Hemi Orange, and Street Hemi Orange. You need his Race Hemi Orange. I believe the only difference between Frank's Race Hemi and Early Hemi Orange is a slight shade difference simply due to paint lot variables.