There is no simple answer to the question. Bikes that come with a chain rear drive also come with a factory recommended slack using a recommended method of measurement, and different models and different brands will have different recommended slack settings depending on various factors such as suspension travel and length of swingarm. I'm guessing you are talking about the belt drive Harley you converted to chain drive, and I'd recommend you follow the same procedure Harley recommended for the belt drive and use the same specification for slack. If you find the tightest point on the chain and set the slack at that point, you should not have to worry about the chain being too tight.
JMHO - Jerry