Slant-6 Electronic ignition.... information needed

How did you guys running the HEI module determine which way (polarity) to hook up the pickup coil? I 'spose you could carefully scribe the dist. body at the center of the no 1 tower, then by trial and error, aim a timing light while cranking over, at the scribe mark, and pick the hookup that "sparks" closest to the scribe?

I'm running an HEI on my Toy 20R powered dozer, and cannot for the life of me remember how I got the pickup coil correct.

If you do use an HEI, make sure you mount it on a heat sink of some sort, clean and flat. Thermal grease doesn't hurt, either.