I don't personally own Finale, but I understand there is a "Canonic Utilities" tool that allows you to do such transformations.
According to this site on Finale's page, you can find it under Plug-Ins => Scoring and Arranging => Canonic Utilities. I admit that I don't fully know what you're looking for—exact inversion, or inversion within the C-minor ...
You can choose the split point: it is some where beyond the plug-ins like arrangemement tools. You can choose any point like e.g. C3 or A2 etc.
You can give in the pitch or the midi number:
In Finale you can create your own shortcuts:
Esc => tool selection mode
tab => simple entry (pitch tool: ô)
from here you can with Alt and numbers 1,2,3,...