Streamline now make Brake Levers and Clutch Perch/ Levers. Mine are on their way and looking forward to testing them out. Also doing the Honda Master Cylinder conversion at the same time using Streamline brake lines.
The worst thing about the DS450 clutch lever is it smashes my finger!
You will need to firstly get hold of a TRX450/700 front master cylinder and then some new brake lines (straight, not bent like the DS450, although some people have just bent the ds450 ones straight. I got Streamline dual lines and they work great). Other than than, put it all together and bleed and you have better brakes. Check these two threads out: