Epilogue - it looks like I misread this.

I was looking at the specs for a 617 engine when I made my determination. I checked again, and I'm pretty sure I'm around 13 degrees. But, I have a 616.912 with the 19 camshaft, which we've determined matches up to the specs for the 10 camshaft. So, the spec for a worn-in chain on that is 11º.

So, I'm a little beyond that, but not to the point where I'm going to worry about it yet. As of now, the plan is to leave this chain in place and check/monitor this at every valve adjustment.