For leds test all you need is the cpu and pia 1. Remove all the other roms and any ram that is socketed. The system still needs a clock and a reset.
You can check the reset at TP 8. It will start low and then jump and stay high.
Here's a video to check the clock.
Note with a dmm on the clock you'll see ~2.5 if you don't have a scope
I'm not convinced the cpu activity is actually the cpu running. It could just be floating voltage.