I really don’t believe you have a bad ignitor. But here’s the link anyway, skip to page 3
https://www.buggiesgonewild.com/showthread.php?t=141085
What kind of compression does the motor have?
Was valve lash checked?
What kind of condition are the clutches and belt in? Were they checked by your guy?
What model/brand spark plug is installed?
Does it have a stock carb or aftermarket?
Is the oem airbox complete and is the lid completely sealed on the airbox?
Usually lack of power up hills or with additional weight leads to a clutch or belt problem. But could be low power from a worn 30+ year old engine. Likely with 30+ year old clutches. Just because it bogs down doesn’t necessarily point to an engine problem if clutches aren’t working right. Take a manual transmission car and try to go up a steep hill in 5th gear at 30mph. Same idea.