I read through past posts about this subject and it seems that for the 60' RailKing passenger cars 1:64 figures would be ideal, but they aren't available in any meaningful quantity.
S-scale figures were mentioned which don't exist.
Next came 1:75 which some said were too small for those cars.
Everyone agreed that 1:43, 1:48, and 1:50 were too big (heads stuck up past windows)
Then Railking people (whatever size they are) do fit, but you have to paint them.
Lionel pack # 6-83653 purportedly fit (whatever size those are), but it says they are for 21" cars.
GGD Little People were mentioned. No size given.
Yikes !
Anyone have a suggestion?
Thanks,
John