There might be someone, but I never heard of anybody there that does them. If you want a bit more power, but still legal, you should look for the 25 amp "250W" version, which is basically the 500W BBS02 badged as a 250W. I'm not sure where you get it from, but I'd try Brighton E-bikes first. You can set the speed to whatever you want, though 15.5 mph is the legal limit with a 10% tolerance on it. Bear in mind that if you want to go fast, you'll need a strong battery with enough capacity. Don't think about getting a cheap one unless you want to run with low power.
Your bike looks good as a donor bike. You might want to think about getting the optional gear sensor with your motor to save mashed gears.