For comparison, I've posted a pic of Peter Winnen about to launch his winning attack on Alpe d'Huez in 1981. Clearly not the same frame size:
Click on pic for larger image.
Perhaps the text at the Koga-Miyata stand was just poorly translated?
> Following Angel's note:
> Cycling news may have been told by the marketing people at Koga that
> this is Winnen's bike but there is absolutely no truth in this. Firstly,
> Winnen is a little sprite of a man and would never fit on this 'big'
> bike. Secondly, this bike has clinchers on it with rims having labels
> that weren't even available at the time. It could perhaps be a team bike
> from 1981, but that would be as far as you could go.
> Steven Maasland
> Moorestown, NJ