[earossi]

I'm actually going the other way from you! I'm backdating a 993 motor so that I can put in different cams and be able to time them via the old system. I did this for several reasons, not the least of which is that to set up the normal, non-keyed cams on a 993 requires special tools to lock in the cams and TDC on the motor before tightening a bolt that fixes the cam sprocket to the cam. These tools are about $1200. And, I don't like the idea of friction being the only element to lock the cams to the sprocket. So, I am back dating my cams.

Unless there is a particular reason why you want to move to cams without a way to key in the sprockets, I suggest that you consider having the necessary keyways machined into your cams. It is not expensive. And, all of your "old" style cam timing sprockets are then a perfect fit.