I read this and thought about it and I didn't think it would work.
I grabbed a G2 and my alpha which has the standard optic and tried it out.
The standard optic will fit in the head. I assume the flood will too.
I found an old p60 bulb and put it in behind the alpha optic. I did not tighten it down the whole way but it did light up.
The beam pattern wasn't very good.
I wish I had an alpha flood lens to try it out.