Yeah that's great, should be a good setup once you get it dialed in. It's really hard to give tuning advice over the internet. I usually run the 14 instead of the 15 because they are cheap used and I don't notice much difference in performance but the jetting can be pretty different between the two. Also if it's a clone, you're kinda on your own, hey that rhymes. There are so many differences and qc problems with clones lots of things could be wrong. In all honesty going to a complete used 14 is probably the easiest way to get closer to being tuned, esp if you got a clone.
First check that you don't have any air leaks at the carb mounting, if you don't have an o ring in there, it's good to add one. Almost all bings leak a little without an o ring. Also make sure you don't have an exhaust air leak, or any other leaks for that matter.
Next, the main sounds like it should be close, might go up or down a little bit, tune it at wide open throttle. You'll have to get the main as close as you can for the needle jetting to work right but as you change the needle and atomizer, the main might change again. Usually it's easier to go big on the main for starters and work your way down as you lean out the bottom end.
The bing design is not very forgiving since it doesn't have any secondary jetting system. The slide, needle and atomizer are all you have to mess with. Reference Myron's page here:
I usually start with the 1/14/196 settings and go from there, the airbox is a big restriction so removing it dramatically changes jetting. It's always better to start with the pinto/magnum guts since they had a less restricting filter. For kitted bikes usually the 24 with the slide mod (search on the forum for 24 slide mod) works the best, but the 51 slide is sometimes better for stock cylinders or if you have more air filter restriction.
Ken will probably come back and say everything I'm posting is wrong (Cunningham's law, look it up, lol) and he honestly has a lot more experience with these than I do, but he can be a real dick if you aren't doing things his way, see above. Teach a man to fish, blah blah, you'll be fine with the 15, just gotta dick around a bit more.