I also used the same 4x3 LED Array to convert the Dome Light as follows:
I joined two 4x3 LED Arrays. Staggered the positive and negative connections, soldered and covered with standard insulation tape.
Removed the standard incandescent bulb (8 watts) and inserted the 31mm festoon connector. Tucked the excess wire up into the roof lining. Fastened the Arrays using the double sided foam supplied with the kit. The slight angle of the surface where they are fastened actually helps to spread the light.
Tested the install before replacing the cover. Initially, the polarity was incorrect and the LEDs did not work. Simply removed the festoon connector and re-installed in the opposite direction. All worked fine.
Replaced the Dome Light Cover, and there you have it. Much better rear illumination and lower power consumption (approx 4 watts for both).