Unhappy 360 (At idle)

a dyno run is in the plans
If its a performance pull (not an emissions check which we used to do for state inspections) then you will get the most out of dyno session by having a goal and plans.
If you want to hook up an oscilliscope, discuss that first. Not many dyno shops do that. In fact most won't even understand why that might be useful. But that's what would be most useful for ignition diagnostic.
Find out what the dyno and the operator is capable of. An acceleration pull usefull for wide open throttle, full load. Use it for that.
If the dyno can be used for other things, and the operator knows about how to do it, you can do more.
But before all that, I suggest you measure and plot the mechanical advance.

Might skim through this thread
Need Opinions. Have nothing to compare to.

Engine dyno threads that have some relevance to goals and collecting useful data at WOT on a chassis dyno.
383 rebuild - kinda whimpy on the dyno?

2 different dynos,2 very different numbers.why?