Hi MR0077:
I am glad you got your wiring problem sorted out! Can you remember exactly which wires were connected wrong? Were these wires that were connected wrong those on the back of the tach or elsewhere?
Now, as far as the ballast resistor is concerned, it was recently added. The "floating" was present both before and after. I added the ballast resistor after frying my 605 when testing the kill switch. You may be just be lucky, so far, in not using the ballast resistor with your Unilite distributor. Here is a link to the ERA website for a Unilite and MSD wire diagram. Also, in talking to the Mallory techs, they advise the use of the ballast resistor and power module to protect the 605 unit in the distributor.
My advice...
without a ballast resistor:
do not jump start your car
do not use the kill power cockpit switch with the engine running.
Either of these actions could send an impulse or voltage surge into your system and without the ballast resistor, the typical item to fry is the 605. (the 605 is the little electric eye sensor inside the Unilite). ((I now carry a spare 605, rotor and cap with me just to be safe... sigh))
http://www.erareplicas.com/427man/wiring/msd.htm