Going back to the OP, the question was what was the best Legacy locomotive to pull a GGD 21" set. The easy answer is the Latest Lionel GS4 or the Legacy Alco PAs. They are prototypical and have the features that were stated as a must have. We all know the Daylight Cab Forward is a fantasy scheme.
I didn't see anywhere in the OP that a direct color match was a requirement.