You can manage some level of porting yourself. There is hidden power in the head, and there are experts here who will unleash it for you, but for year 1, it's not beyond you. Perhaps save dough where you can but invest in a good cam. However if you get a hardweld cam get your rockers hardwelded as well. Cams aren't horrible but getting the rockers welded is $$, but after four race seasons mine look like new.
Stock carbs will work fine to get you running. TG mentioned the Mikuni VM26 carbs. They were used on many bikes but look at the 70's Kawasaki's and since you have been doing your own fabrication, you can alter the intake manifolds to match the Kawasaki carb spacing which is close to Honda's port spacing. In effect your straightening the "S" out of the manifolds. I went this direction too but in the end switched to 29mm Mic smoothbores.
If you have the bottom end freshened, the head/cam/carbs can be breathed on at a later date. If you're going to the track you might want to put longer shocks on the rear. Perching up the back end will reduce the rake and help it turn plus give a little extra ground clearance. However, if you do this it should be noted there is a loss of trail. TG used NSR125 triple clamps (35mm offset instead of 45)which is another easy solution and brings the trail # back to near stock. Fork spacing and diameter is identical.
Even a stock engine in a chassis that turns, handles, and brakes well is way more fun to ride than a stocker with an engine making twice the HP. Better to focus on these thing first.
