Imho while there is a chance the probability of a Campag/Fulcrum freehub fitting a Miche hub is not good. The whole hub/freehub interface including the pawls/springs would need to be a marriage made in heaven (which in this case likely meaning Miche badge engineering Campag's hub) for it to work.
The 707 does come in a Shimano freehub version, which would mean that Miche will likely have parts. The question is whether the respective hubs are identical (likely) and whether they would sell you one (also likely). Questions though remain as to whether it is economical and whether it is really what you want.
Assuming you have indexed shifting surely your choice of cassette and therefore freehub/hub/wheel is decided by your shifters (what are they?). While you can space your Shimano cassette to Campag spacing and vice versa, it is often not an economical or trouble-free option. If I were you I would list all the bits I have and see what will and will not work together before buying any more bits.