I made a reasonable effort to copy the weather and colors used on Gold Leader (the model commonly called "Tie Killer" on places like the RPF). There's more rust and green on it than you can see on the 1970's era film stock. It's a very colorful model. It always looked very white and stark on film. I got pretty damn close to the available images of the model. It's not just the painting - you need to scratch up and sand on the paint to get the right look in places.
Also I didn't realize until working on this the Y-Wings did not have astromechs during the trench run. They had empty droid slots, hench mine is empty as well.
"Tie Killer" (named for the tiny kill marker on it's nose) is in private ownership and hasn't been seen since ~1977. It was not available for Empire or Jedi - the hero Y-Wing in those films was built by Bill George. He built that Y-Wing with the available refference of the day and it has some proportional differences from the Y-Wings in SW.