That had me musing for a long time and I'm still not sure. Maybe CrazyLegs knows about that colour change in the horns?

I looked at loads of pictures of the 80s-90s Rams especially Dickerson and the horns can appear yellow or that slightly darker yellow/orange. In the end I just went with the colour that I remember as a kid and also what I found available on eBay!!!

Many thanks to all for all the positive comments by the way!