Rg,
I'm catching your plan ...and I like it .
I am going in stages. $400 worth of stuff to replace all the mounts and shocks and the damaged exhaust.
Exhaust is a tuned one, but still looks OEM. Good for the next stage...
When I replace the cylinder I will put in a 210cc, 7 ports, with the 60mm crank. That gives it a lot more HP and torque without kill the gas mileage or risking the engine. Will need jetting, but since it is a 28mm stock carb, won't need a 30 or 35mm.
Should be about 18hp or so, with 100+ mpg and good reliability with the iron sleeve vrs the Aluminum one.
Aluminum one gets up to 20HP, but you are much more liable to soft seize on long rides.
About $500 with all the bearings and gaskets replaced.
Ps. 20hp sounds dinky, but the bike weighs 220lbs, and it is direct drive, no belts or chains.
Power to weight is in the class of the CB550, although it will not "do the ton".
They are damn scary bikes if they have the light 3 lb flywheel and other mods to drop weight. Stock 8lbs lets it cruise all day long, but slower off the line.