Lionels Big Boy:
If you don't care that it is too short, and too tall. About 10 feet too short and 2 foot foot too tall.
It started life as a "O" gauge model then went through several iterations and was acquired by Lionel. it is NOT "S".
Lionel pulled the opposite long ago with the 027...... "S" gauge models on "O" gauge track????? That made it very easy for some of us. Toss the couplers and the trucks. Kadee's and scale trucks and your off and running.
I have no proof other than total rumor but I was informed that Lionel has every intention of redoing the Big Boy into a respectable S gauge size model.
My understanding was the K line Big Boy was a quick total sell out.
I do know that it isn't even a stand in for the scale guys where the Lionel Challenger and Y-3 are supurb, so are the new diesels.
Yes, there are scale guys that will buy the new Lionel along with some of the older AF for conversion purposes. All of the older Gilbert that I've converted over the years at least started life very close to scale, very close. The couplers I tossed along with the trucks. I grind a lot of the details off and added brass parts and a new paint job. (I never heard of a real railroad named, American Flyer).
I no longer cut up AF passenger and make them scale length. I have too many Flyer collectors here that would have the big one if I did that, besides, they keep me supplied with all sorts of older scale stuff from the 50's.