Actually, Colt did experiment with a .40 cal. Navy but it never made production.
Serial no. 1 had a 7-1/2" barrel
Serial No. 2 had a 6-1/2" barrel
Serial No. 3 had a 5-1/2" barrel*...right up your alley, Hewy!
Reddish Uberti-style grips, steel TG and BS, non-rebated cylinder.
Apparently it was an overbore of a .36 cal Navy.
I would post a photo from the book, but it would probably violate copyright laws. Shoot me a PM if you want to see it...
* reference Colt, an American Legend, RL Wilson, pp. 56