Nice work argonaut!!!
I was going to mention that my BB ended up about 4'' away from the radiator IIRC so I went with 2 12'' fans and mounted them diagonally to avoid the water pump pulley.
Also want to mention that Flowmaster 40's are LOUD!!! I have them on my shortbed with sb 400 and the truck rattles my house and is extremely loud driving. My BB has 50's and is nice sound, typical Flowmaster, not too loud. Dont know what your plans are for the truck, so I thought I'd throw it out there for your consideration..