When you rebuild your carbs, DO NOT buy a "keyster" kit. They suck. Look on EBAY or at the dealership, Dime City, etc. and piece together what you need. I highly suggest finding a factory Honda manual. (Also an Ebay deal)
Being your first bike I would highly suggest NOT tearing the engine down. Clean it up, check tolerances, and replace the top end gaskets. It can get real complicated and expensive when you start taking a motor apart.
And as far as top speed, the fastest Ive ever gotten a mostly sock 350 was into the upper 80s. Youll need some real weight shaved and performace bits added for much more. The high end 350 race bikes barely run at 105.