Well first of all, there are many, many ways you could
approach this. If you are working with NURBS then n-gons are
not an issue, as n-gons are only relevent in poly modeling.
unless you mean n-gons on converting from nurbs to poly. You
could definitely create cross sections and loft the nurbs,
but that is pretty time consuming to get all the proportions
correct. Also texture mapping can be trickier.
I know maya's modeling tools much better, but the
principles should be the same. For speed, if it were me, I'd
take photos from top down and side, then set them as image
planes for reference. Then I would take a poly sphere and
rotate it so that the poles were aligned along the
horizontal x-axis (lying on it's side). Then I'd create a
loose grid deformer around the sphere and push vertices
around to match the reference frames
OR
you could also begin with a subdivided cube, and model half the
unit (cut in half along x-axis). Again, using the images as
reference and enough vertices to approximate curves, you push
the vertices around until it's an oblong squashed shape. Then
you mirror the model, merge the vertices and apply a subdivision
smooth. This would better allow you to model the inset cutaway
