well i have the sound version "Columbus"-almost identical but not Disney and has sound-year and years ago these sold on close out for 550-LGB digital sound feature is roughly worth about $300 upcharge -so you see -about 300-even with later price adjustment
i believe your loco came with a set with 2 cars-and was only available that way-the set retailed for a whopping 900-but that isnt what they sold for typcially -about 650ish as i recall-so this might give you a 'leg up'
im certainly no expert but do keep abreast of prices used and new-heres my best guess-worth what youll pay!!!........
assuming its set been broken up, and the loco is pristine and with little or no running time
id guess maybe as high as $400-that is, the some what based upon the following : the old price on the Chinese forneys was pretty much around $300 (when they were available)-then add yours is a 2-4-4 (to me more desitrable than the 0-4-4 version), the scarcity of Forneys in general now, and the Disney factor -to the right buyer it may be worth this amount or more-its a double market- LGB and Disney types-the downside is that these are a rather bright color scheme and not to everyone's taste for 'train types' -having no box is, for me, generally a 'no deal' as it raises, to me, right or wrong, issues of condition and care and, resale value to a 'collector' -if you find a buyer with a bunch of the Disney cars-face it theres only a few Disney locos-the outrageously expensive mogul and yours-the rest i think are Toy Train versions-so its sorta special to the right buyer-it could be higher-but premium prices seem to go with items with original boxes etc
considerably less $$$ if loco condition is less than perfect, broken or missing parts, etc-altho with ebay ive seen some frenzied and not so prudent prices
if yours is german made that is a plus as it is percieved as a better quality by some-may add $50 or so