Can you put a Wilson combat 320 grip module on a P250

Possibly. If you have an older P250, you may need a "new style" slide release lever kit from Sig. A call to Wilson should answer your question fully.

I have a later made P250 and can confirm it works with Wilson modules. Those along with a compact upper expanded how I can use it as it originally came as a subcompact.

Well, that's kinda nifty