One approach is to add your reference lines as expressions instead of as reference lines. The labels will then show up like any other label in your report, which is to say they'll be separate and won't overlap anything. In my case, I put the numeric value in the label as well for clarity, such as "2009 Business Plan 98.87%".
While you can't put the text in the chart that way, you can put the numeric value in the chart instead of in the label if you wish. Add a second copy of the expression, but as if(condition,expression) where the condition only matches ONE dimension value of your choosing, and checkmark line and text on data point. With only one data point, no line will be displayed, but you'll get the number to display above your "reference line" on the data point of your choosing.