if your 650 is stock you could coax a few more HP out of it with an aftermarket intake air filter and exhaust, and rejetting the carbs.
One thing to do is check your stock air filter, if its not white like paper, replace it. Its surprising how much power a dirty air filter will block, it is the same as keeping your throttle from opening up all the way. If the engine cant breath, it cant scream.
If you want another option, there is a Vstar 950.
One more thing that is worth pointing out: Vstar bikes are Vtwins like HD, but harley makes a long stroke, low rpm, high torque engine. Vstar engines have a shorter stroke and a much higher red line.
If you are riding your Vstar like a Harley, lugging it around and shifting it too soon, you are not hitting the peak HP of the engine.
on the 650 the peak HP is at 55mph in 4th gear, and 70mph in 5th gear. There are a couple websites that will tell you the RPM at any given speed, in all five gears.
The 650 is already a fast bike - it will do 100mph. If run WFO up to 55mph in 4th, the stock air intake growls with joy, and does it again at 70mph in 5th.
Maybe you just need to shift a little later....