Success! All in all it wasn't a bad job. The rear cam cap was pretty easy once I found the diagrams.
The chain in this motor only had two colored links. I spun the motor around until the one colored link I could see matched intake actuator mark, making sure the motor was set to #1 cyl at TDC (exhaust stroke) per the FSM. That put the timing marks for the actuators in the correct location (10 and 2). I colored the chain link on the exhaust side with a marker just so I knew where it went if the cams jumped when I pulled the tensioner.
With the tensioner removed, there was plenty of slack in the chain to separate the actuator from the cam & reinstall the new ones. Nothing difficult about the reassembly.
I put the cams side to side to compare the difference between the 2010 model (correct for this vehicle) and the 2011 (flex fuel) version.
The locating notch on the cam (that aligns the actuator) is 180 degrees apart, but I knew this because of the GM bulletin. Beyond that, the cam lobes are timed different in respect to a) the camshaft position sensor notches and b) the actuator notch/index. If I held them together as they would be installed in the vehicle, the cam lobes were a good bit more advanced on the 2011 cam. The cam grind seems the same otherwise.
I definitely had my fingers crossed when firing it up for the first time, and was greeted with some sputtering and a quick stall. Second time, she ran beautifully. Cleared codes beforehand and after a 10 mile or so test drive, it runs awesome with no stored or pending codes. Reading engine live data, the high pressure rail is around 600 psi at idle, and ramps up higher with RPM/load, just like it should be. With the 2011/wrong cam it was pegged at 2500psi at idle, and would drop with RPM/load.
Glad I solved the puzzle and many thanks to the forum members who contributed in making this repair a lot easier than it would have otherwise!