Is my 27 a 6 volt or 12 volt

I have a regular coil and distributor.

Hard to tell without seeing a picture of the coil. Generally the coil will say 6V or 12V on it somewhere. The charging system mostly doesn’t care other than the cutout on a Model T. Some of the reproduction cutouts are voltage regulators and some are also polarity sensitive. Again pictures can help a lot.

Look at the battery. A 6V battery will have three cells. A 12V battery will have 6 cells.