I was aiming for about 330-350mA but final circuit is more like 240mA.
That resistor and Vbe set the current. For 350ma, you need the resistor to be about 670mv / 350ma < 2ohm.
Linear constant current drives like yours are best for small power applications (<1amp in my view). Your circuit works, and I personally prefer the LM317 based solutions.
For higher current drives, you should really go with a switching regulator. The $1 SimpleSwitcher based board from ebay can be easily repurposed for this application. If you have a few spare pins on your arduino, you can also program for this purpose as well.