I've swapped 727s in place of 904s before, but never the other way around.
And I was quite surprised to see the 727 in this truck, I've had several of these trucks with V8s and 904s, and both my dad and I had 3/4 ton B-vans with 318s and. 904s. And here's a /6 powered (I think it's even a D 100 not a D150 even) with the lightest gvw they made during those years with the 727 from the factory. Weird.