You dont, I have used the ordinary coil with no problems but if you have the correct one use it.
I advise steer clear of the bright red ones sold on ebay for about £40.00.
I have had dealings with five of these & they have all failed.
Derek.
You're worrying with this Delboy. I bought one of those electronic ignition kits earlier in the year, and haven't had chance to fit it. Was hoping it was going to save having to play with the points, but I am now having serious second thoughts.