As far as the listed multivars at racingplanet for the Like 50, do note that they are different malossi part numbers. Malossi 519988 is the one for our scoot. Malossi doesn't 'identify' our scoot yet, but the engine on the Like is the same as the one found in people 50 2t, cobra, & super 9 ac. A lot of shops are currently out of it.
As to carb, the 17.5 would make a slight difference over what is currently in our scoot, since the fuel/air screw can't be adjusted and neither can the needle (without shimming), plus the stock carb is a 16. Although I have found on different forums where a bbk has been used with a 17.5, a 19 (at least) would be preferable. I know you are putting that off for now, but in the long run, for a few dollars more now (should you decide later that a bbk would be best) you will have exactly what you need then and not have to purchase another carb.
If, in the derestriction process, your shop did anything to the carb, you are likely on an 82 main jet, especially if they sell Kymcos. Given that you are on a stock exhaust, if they did not touch the carb (and assuming the previous owner did not as well), you would have a 78 main jet and should be okay, though a little lean (as shipped by Kymco for EPA purposes). I would def get a selection of main jets for tuning purposes. From experience, it is better to have a few on hand rather than having to wait for them to be shipped. For your current (stock) carb, this is where I get mine (and the link is for the exact size thread):
http://www.jetsrus.com/a_jets_by_carburetor_type/jets_keihin_99101-116_main_round_small_and_38-xxx.htm
