I'd get a new piston and rings (OEM Honda, next size up), piston pin and circlips, camshaft bearings, cam chain (new tensioner depending on how yours looks), head gasket and cylinder base gasket. OEM parts are the best, just make sure you order everything at once to save on shipping.
Do that and your bike will be good as new, assuming the bottom end is ok. I wouldn't bother with putting an oil cooler on this bike. If you keep the oil fresh, and the air filter clean, this bike will run forever! Check the oil level frequently and keep it where it should be, no more, no less.
Oh yeah, and new valves and valve seats if needed... Take the head and cylinder to a good machine shop and they'll tell you what the best options are for what you've got.