A4 Trans questions

[Transporter9033]

I am just in the planning stages right now but I will need the information sooner or later so I am asking now. I realize that with the engine I am building, I will need to get my A4 transmission rebuilt. I already have a builder in mind too. The thing is, I need to figure out which transmission to use. Here is the deal: I have the stock transmission in my '95 Z28 now with 107k on it and I have a stock '94 A4 out of a 9C1 ex police car with a little over 200k on it. They both still work fine too.

Here are my questions,
I have heard that the transmissions out of Impala SS's and police 9C1 cars were better to use for street/strip rebuilds. Has anyone else heard of this and is there any truth to it?

What, if anything, would I need to change to put a '94 transmission into my '95 Z28?

And lastly, would it even be worth my time to put the 9C1 tranny in there?

My thought process is to rebuild the 9C1 trans while I still drive around on the current trans in the Z. Sound good?

Thanks,