Ignition problems I think

You gapped the plugs and they are correct for the application?

I have to ask, the plug wires are in the correct firing order 1-5-3-6-2-4

You say the spark at the plugs seems weak, how does it look off the coil wire, nice and blue?

I would say that if you are getting spark there is nothing wrong with the coil and ignition module. Were there points in the distributor when you put on the new rotor? If so then it's not electronic. For it to be electronic there would be a reluctor and pick-up assembly in it.

What is the voltage reading on the coil + while you are cranking it and what is battery voltage while cranking?