I had a lesson yesterday and found myself having the same problem as you did Bill. I have always been an overlap grip person and have tried interlock a couple of times, too uncomfortable. My instructor found a fix for the club-twisting and also a drill for it. The problem was not whether or not I was using overlap or interlock, it was that my finger pressure of my right (for righties) index finger and my thumb had too much control in my right hand - causing me to grip too tightly towards the top of the swing, and losing control.
The drill she recommended was simply called, "The Claw Drill".
After assuming your address, grip the club normally - then instead of placing your index finger and thumb around the grip (as normal), you put your index finger and thumb on top of the shaft but the tips of the two fingers are still connected. Essentially, you will find that your grip pressure has to be in the last three fingers of your right hand.
She said she played a whole round of golf like this and played one of the best in her life, she said it helps those that cast and rush the downswing - I tried it and it worked beautifully.