How can I convert 3d scanned files from 3df Zephyr to solid bodies or surface bodies?

You are welcome to try our InStep Studio 3D application for this.
From a quick look at your file, one of the main issues to contend with is that there are a lot of holes and not all surfaces are connected. The InStep application can fix this, but keep in mind there is a learning curve to this (as with anything worth anything in life), so if you have a poly-editor you are comfortable with using, I recommend you start there and learn the InStep options are you get more comfortable with it.
Once you have a (ideally single) water tight body, you can use the Reverse Engineering tools (Rev-Eng tab in the Expert Interface) and generate NURBS patches. See the online help to get started.
This will generally create a solid body that you can then use and edit in other mechanical CAD applications.
I have 'processed' your file and the steps I took in the InStep application are:
1) import file, split body
2) Bodies: select main body and right click, delete all others
3) Repair: Wrap, use Shrink Wrap (Edge Length=2.0, Iter=4, Factor=0.1) (this will take some time... use iter=0 to see the preview of the mesh spacing, iter=1 with factor=0.8 to do a more coarse approximation)... this is step is very much trial and error, so feel free to play around.
4) Export to STL (a kind of Save option)
5) RevEng: Auto Seed option: Aligned (default options) - Generate Preview - GENERATE.
6) Save Surface (or Export - STP)

I have performed the above and uploaded it here:
Front Cover
(also a version where at step 4, it is saved to STP)
Let me/us know if this is useful...