You can do some reading to understand how the PHBG carb works, but as I understand it, the carb is supposed to already have the the appropriate components to work well with a 49cc to 70cc 2T scooter engine. Maybe not?, but I bet it's pretty close, except for the main jet. If you get into it, I think you will find there are literally 1000's of combinations of jets, slides, needles, nozzles, it will be overwhelming.
For awhile I was favoring Arreche, but have come around to Dellorto, or maybe a Dellorto clone carb. Arreche are not readliy available except from RacingPlanet. Everywhere I look they are out of stock. Maybe RacingPlanet has exclusive deal with Arreche, I don't know. I like RacingPlanet fine, but don't want to be dependent upon them for parts.
MotionPro got back with me about making a custom throttle cable and I don't think that's the way I want to go. You send them your old throttle cable and the new carb. Then they cannibalize your oem cable to make you a custom cable for $55 plus shipping. With the cost to replace the old cable, shipping to MotionPro, plus their charges, seems like too much for me.
The light finally came on for what to do about the throttle cable. I now realize can probably make my own custom throttle cable, just the way I want it, for not much $'s. I was clueless about the cable splitter and kept looking at them and finally figured out how they work. The cable splitter or 2 into 1 junction is what I was looking for. It's function is very similar the throttle plate I was thinking about, but simpler. I've been looking at some vids about making custom control cables and think I can do it. Not sure I would attempt to make a brake cable, but throttle cables don't take much load, should be a good place to start and learn how. Cheers