I agree.I would give up that idea. Round hole, Square peg.
What's in the existing bathroom now? Not trying to be negative but just because you got it for free does not mean you have to find a use for it.
I've learned my lesson. :whistling
I have come across "free" jacuzzis on numerous occasions. If I was going to do a bath remodel, I might have considered using one, but for the amount of time the jacuzzi would see use (1%) vs the time the shower would see use (99%), I think I would regret it a lot.