Since my volunteer is already on the levitation board, I was planning to combine the visible sawing with it before I proceed with the levitation. What do you think? Or, should I do this separately with 2 volunteers instead?
I haven't used my visible sawing for years, I was just planning to revive it.

Visible sawing while levitating!

It might be ok to do them both with the same volunteer, but it really depends. Some volunteers want to get off stage and back to their seats, and doing two illusions with them may seem like too much. But if they've "done so well with the first one" and you'd like to "graduate them to the next stage of magical assistantry," go right ahead. Getting a second volunteer after cutting one in half may be problematic.

Great funny idea. I like it.
Actually one should be the reason for the other one. You choose.
You have somebody come on on stage to be cut in half. The blade jams in the board (or similar conflict) so you remove the board (modified version with stooge in the house).

Or

Have a volunteer on stage to make her float. Make it a poetic parody. You hypnotize her, eyes closed so she does see the jigsaw. Cover her with the blanket. etc. You put your construction ear protection in case she wakes up!!!

I really like that. There's conflict so it's theatrical. The magic performance becomes it's own story, it's own reason to exist.