Do not part with the Glock!
NEVER sell a pistol! When I purchase a pistol I look at it in the same way I look at money I spend on gas. It's gone. No getting it back. Do NOT sell your Glock! Hell, it is only going to go up in value and besides it makes a heck of a gift to your kids and/or grandkids!
That said, just buy a 9mm conversion for your G27 and KEEP IT!
Oh, did I mention you should hang on to your Glock?