Looking for the two red color paints for the Lotus 78 Imperial that ran the Japan Grand Prix.

The Lotus 78 which carried the Red Imperial Color used two different red colors.

First, the body. Use the MONZA RED (Ref: Gunze Mr. Color #68).

The front wing and side pods/side pontoons are mixture of two colors. Basically metallic red.

Mix Red + Gold (Ref: Gunze Mr. Color #3 + Gunze Mr. Color #9).
Mixture rate, when I made the model in the past, I've used 1 part of red and 1 part of gold. But, if you can get your hands on the actual photos, maybe other members can help you, it is best to use it as a guide.

Hope this will help you.
TF