it's called "light ruby red" but there isn't much "light" about it. Don't know the codes, but from what I researched, there are no true paint codes available for it. Honda used a "light ruby red" on many other bikes, including the 1971 SL70. I matched mine to a color chip at auto paint store. Don't remember what color I picked except that it was a Chrysler color and matched fairly closely. Guy in Dallas that restores SL70s has a nice light ruby red that he'll ship to you that matches the SL70 color.
http://www.marblesmotors.com/CustomPaint.htm. Now I've never seen the MR250 light ruby red up against an SL70 light ruby red, but in my mind, the MR250 color is deeper and darker. But I really don't know. Might call the guy at the website and talk to him about that. Or just take you tank to a good auto paint store.