Bin flipping me faces in trueSpace. When I load the DXF, each chunk of the model is inside-out bar one probe thingy on the nose of it [

], so I just select Flip Face and click the various sections until everything's A1 SUPAR.
As for the Blender knockers out there - in game, this model has one 'issue' that I can see, but that may have to do with me putting a couple of faces too close together. I'm experimenting to see if I can fix it, but if I can't then I'm not too bothered since this little forray in to the big scary world of 3D modelling has already gone above and beyond (

) my expectations...