are you referring to just a bulb to see when the points open in relation to the crank position, or a regular timing light on the running engine?

A regular timing light on the running engine would be be best.

but the ones on my B9 generator are, and I could swap them in, or, at least put one on #1.

Swap the lead, the cap & rotor.

But if the wire were bad, would the plug still throw a solid spark?

That isn't all that meaningful. Try checking for a spark while they are hot & have 190 psi of air pressure applied to them.

You did rotate the injector to another cylinder & leave it there right? It's not stuck open?



--
Three 164's, Two 144's, One 142 & a partridge in a pear tree.