Keep an eye on the BigBike PSAs thread on The Paceline:

https://forums.thepaceline.net/showthread.php?t=107521

Many of the bikes people find turn out to be vintage (or nearly vintage) steel. That's another advantage of steel. The bikes could be built in pretty much any size. I don't think there is any profit in large frames for the carbon fiber types.

Also, you will have to forgive the "little people" who post to the thread thinking 61cm frames are "big."