Anybody here good at sculpting in Fusion 360?

[m_c]

This was a play project I originally done in Solidworks several years ago, then machined via CamBam.

The original SW file loads, but when I convert to T-splines, lots of the curves go the wrong way, so I end up with arcs opposite from where they should be, but cleaning it up gets the attached image.
What I want to do is now transpose/extend that model so it forms that model on top of a flat base, but I've so far failed to find any good demonstrations of how to do it.

Anybody care to point me in the right direction?
Or I can send the file if anybody wants to try it.