Smoothing Out a Set of Surfaces

I am trying to recreate a casting. I have taken the basic shape from plans The red surfaces are the only ones that are fixed. The rest does not require great precision. (I need a flared pipe at the circular hole to make this a solid.)

The casting has rounded edges. So I would need to get every shape edge knocked out. My feaar is that filletedge would puke on this.

I am wondering if there is a better why to create such closed polysrf. (I view this as a prototype for visualizing the desired end result.)

Problem Smooth.3dm.zip (232.1 KB)