I have a forklift with a commercial slant 6

when it quits running, do you have good spark? Is the choke open fully? If you work the accelerator linkage at the carb, can you see fuel squirting into the carb venturi? If you have fuel and spark, you just need proper ignition timing.
You mentioned replacing electronic ignition. Why was that done? What year engine are we talking about? Does it have spark plug tubes? If not, then I think it is an hydraulic lifter engine, which might be important to know.