Welcome to the site!

For the 1978 Yamaha DT125E Leaves Green Paint, you will likely have to paint match it yourself, or take it to a paint store and have them scan it, to make a match. That is what I did. I did lots of testing, of various paints, until I found a good match for the CT1B Candy Metallic Green.

https://www.legends-yamaha-enduros.com/forum/general-discussion/yamaha-paint-matches/dl-f982e0b9-cb6b-4115-9c86-94f8d5bab6c1?srsltid=AfmBOorYjwx0weW4qNC76LhnWvO8Ea-YC13h1mBWvbodLWszMqWgFRE2

I rarely ever sell original / NOS parts, but I do have a tank I would be willing to sell, the paint is perfect but it does have a dent in the side. A good tankless dent repair shop could probably remove the dent or it could be used for paint matching.

The exhaust is flat/satin looking. I am sure you know, but for others, who may not know, you would want to use high heat paint, so it will not burn off.

https://marblesmotors.com/product/honda-hi-temp-exhaust-paint-black/

Yamaha still carries many parts, including the left hand foot peg torsion spring, Part # 90508-20023-00.