Odd timing problem 360

I would try another light. i just broke in my stroker last weekend and had a brand new Equus dial back light hooked up and it was all over the place. we pulled the 30 year old craftsman out and it worked fine. i am running msd ignition and wires. The timing light directions make reference to some kinds of wires causing problems. i made a call to the Equus tech dept and pointed out my problem with the new light, and typical to most tech lines, it was a waisted phone call.