Put a rag in the jaws of a channellocks (slip-joint pliers). Use that to grip the valve.
If you butcher the valve, you'll have to make a hole in the tubeset anyways to install the new interior base...or cut the valve hole bigger and install a valve + doubler
Gluing geek since 2007
Opinions and intepretations expressed are solely my own and do not express the views or opinions of my employer