I like that idea. I definitely think the Inquisitors should be involved.
It would be silly not to. You can't have Vader show up again and the advantage of the Inquisitors is that there's a lot of them and whenever any die they're quickly replaced.
Honestly I'd love to see what happens to the Inquisitors. They're obviously not around any more in the last few years of the Empire (Vader would've just sent them to find Luke for him), so maybe Cal can be involved there somehow.
Would be pretty cool if Cal and Ahsoka teamed up to take out the Inquisitorius once and for all.