Dave,
I have a 59 Ambassador International twin (center) with factory bunk beds. I
realize a lot has changed between 59 and 78 but if you're interested I can
send you photos of how they did it in 59. They work really well and make a
great storage spot when we're on the road.
Colin
57 Sovereign of the Road,
59 Ambassador
65 Safari
50 Cruiser (with a pipe frame)