The coil impedance is kind of important, but I don't think that is your problem.
It should not make that big a difference, but look at the Pertonix site for specifics.

Also, the timing changes as it's installed. Static timing is not possible with the electronic pickup. Also, the cam-mounted ring can cobble a little, stick a little tape under it if so.

In my experience, D-jet always fails "rich", vey often due to a short in the coolant temp sensor connection, which goes to the sensor at front of the head.

I found this, also:

"This particular Pertronix unit was machined in such a way that the mounting plate that attaches where the points used to be was too wide. In other words, its outer edge fouled the cap, thus preventing the base-plate from being rotated by the vacuum unit. The fix was to remove it and sand off the excess metal on a belt sander. (A file or bench grinder would work, too.) When replaced, it made a big difference in how well the engine ran."

Some here have mentioned that the Pertronix MIGHT deliver a weaker spark with the same coil. I eventually installed a 30kv "flamethrower" coil.
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MPergiel, Elmhurst, IL