I'm sorry to hear this but you have to do what's best for Pouncer and your other cats. When I had Cirrus, this made Storm miserable and stressed out for 2 years and it also made him sick. I'll never do this again.
I'm sure that with Tuscan's sweet personality that he'll have no problems finding another home.

Now for the 2 other cats that will be coming into your home, I really don't know what to tell you except for good luck. Hopefully they'll both be very laid back.