I had no problems just motoring around town with the TFI coil and ballast resistor. I Think the solid-state coil has numerous advantages, that's why I went with it.
George and I had a (respectful) discussion about the Duraspark II wiring diagram and my associated modifications. George, rightly so, stated that if you monkey around with the proven design then "you pays your money and you takes your chances". I have to agree with him there.