Any ZTactical PTT will work with the ZTacticals Sordins
Your only concern is to find a Motorola compatible PTT
Techseller (here on ASC) can help you with that, and he's got incredible service
www.tecnologydirectcanada.com
Edit:
My bad, didn't read the post carefully, I read MSA, Motorolla, ZTactical and connected the dots - bad habit :P
There's a thread somewhere with, I think, a solution to your problem already
Leaving my initial post so it might help other people searching for that