Yes the Vernier cam gear they called it. But from memory it did have a small problem in that the cam position magnet hole was made oversize, the magnet would come loose. No a huge problem to get over if you handy.IIRC rollmaster had a timing set with a 2 piece cam gear that you could adjust infinitely.
Do you have a pic of the offset key ?Update:
I found a key that will work for the 3800 series. I am using a 4 degree key from a mopar. The key is a bit tall, but easily can be shaved down. The width feels perfect and sets right into the slot. It just saved me from having to buy another new timing set. So far I am only into this build for about 1000.00, and I have replaced everything. I am taking pictures of this build as a I go, eventually I will post up some pics, and a short write up of my experiences. There is still alot left to do before its ready go back in the car.