Your best bet is to look on eBay; people often sell Doyusha kits on there.
The last model I built was a Doyusha 1:100 747-100 kit. Here's the finished product (which I custom-painted in my own fantasy airline colours):
I love such huge scale models as Doyusha--they allow more creativity in painting! They're bigger and easier to build, and provide a much larger "canvas" for painting than average-sized models.
Good luck in finding one! I don't know if Doyushas are made anymore, but keep checking on eBay, or ask your local hobby shops for information.
I will praise thee; for I am fearfully and wonderfully made... (Psalm 139:14)