I found out that there is a 512 LED limit on running continuous LED arrays from one output of the Arduino. Then I discovered an alternate setup that can run 1200 addressable LED's from an Arduino. The alternate method uses the parallel output mode to run 8 strings at the same time. So far I am just testing the setup to see if it works.
This picture shows the wiring, it is much easier than any other method of running the addressable LED strings. Since I only have four strings of 150 LED's they are split in half to make 8 strings of 75 LED's each.
Here is my first test program running. I changed the default array of patterns into some text.
I have improved the code to support longer strings:
The sign now breaks down into sections that are each 40 inches long. That is done with eight 3 pin plugs that are identical to what comes on the LED strips.