I did buy a box of various headers, assuming I needed something to connect to the board. I like the look of that part better, so I went ahead and ordered it. Thanks for the suggestion!!
BTW, I just bought a modded 7800 with composite out. It also had the power supply modded to take a 5.5 x 2.1 barrel neg polarity. Since the dragonfly requires a positive polarity plug, I assume that the power output is positive polarity as well. Did RJ reverse the polarity on his 5.5 x 2.1 to 5.5 x 2.1 jumper he sold separately? I assume I’m going to need to build a cable with reverse polarity to make it work with the modded 7800.