Misfire on 1 bank/ '97

[nola mike]

Short version: started misfiring, eventually threw a CEL on cylinder 3. I changed plugs, embarrassed to say I have no idea how old they were. Now misfiring on cylinders 5 and 6 per CEL. I'm getting very intermittent spark to cylinders 4/5/6 when I put a timing light on the plug wires. Smooth on 1/2/3. First thought would be the coil pack, but getting SOME spark on one bank and none on the other seems like a weird failure (but I have no idea how these things are wired). Maybe a camshaft position sensor? I don't even have my crappy Chilton manual to look through the wiring...
Other ideas? Depending on what's involved, maybe swapping the CPS sensors and see if the error follows the sensor...

EDIT: If this is a waste spark system, if one cylinder is firing, then another should be firing at the same time, right?

 

[nola mike]

Just remembered this is an OHV engine, duh. So whether it's the (single) camshaft position sensor or the single crankshaft position sensor that triggers the spark, it's obviously working. So that leaves the ICM or the coil pack, right? If the ICM has different outputs for the different cylinders, then I could have a wiring issue as well, but I don't have a wiring diagram to see.
Also, compression tested the cylinders, I got 125-130 on both sides. IDK how accurate my gauge is, but that (thankfully) isn't the issue.