I'm converting a ten speed road bike with drop bars into an upright sitting bike.
It's going to have a Nitto North Road handle bars and super long stem. With the
old drop bar, the c.g. is probably right between the two wheels. With the new
North Road bars, the c.g. is probably be a lot closer to the rear wheel. That puts
a lot of weigh on the rear wheel, and the front wheel will be very light. Do you
think my new upright setup will have negative impact on the handling of the bike?

In automobiles, the weight is mostly on the front wheels. I think that's suppose
to make the car stable. A rear heavy car would be unstable. I'm just think this
principle would apply to bicycle also.