Dave,
The 1946 ~ 221's were painted Grey, the 1947 ~ 221's were painted Black.

As to repainting your locomotive and tender I'm sure that the paint can be matched if it is not available commercially.

Personally, I don't believe in repainting  unless the original paint is totally wasted.  When you repaint, you destroy the history, love & play the train has received over the years, taking away the originality & individual personality  the locomotive has developed over its lifetime.

So, unless it's a total piece of junk paintwise, I'd just clean it up really well and apply a coat of wax to it.

Dave