Ok, this running off the front sprocket bit is a pain if you're not running the standard gearing.
So, get some MK1 b6 or b12 clocks. Remove the Speedo internal for the clock housing and fit a GPS Speedo in there, just like @fatblokeonbandit did
Speedo will be right no matter what the gearing.
The rev counter will just plug and play same with the idiot lights, and if you use the b12 MK1 clocks you keep the same red line on the clock face as the gsxf750 and you also keep a fuel gauge.