But bench-testing(plugs/coils/starters/etc) doesn't equal working correct under load.
If lack of fuel problem, starter fluid will give one or two strong rotations then die.
I'd try again with a full charged new battery.
I suspect the plugs/gap. It is a custom engine, so sorry no help with that. Check the gaps. The one that
is sparking is closer to correct.
Some basic info on coils here
How to Make Sparks