(1) put in several gallons of race or av gas & bump the timing up to where it should be for your eng (more total/faster curve (lighter springs) cuz your timing is retarded & see how the temp does. (2) What Lewt said confirm your jetting is in the ballpark just bump em up quite a bit for a test just like purchasing the av gas, a one time deal & blocking the rods up (eddy) is one way to do that to put you on the power circuit. (3) if still running hot then I'm thinking there is either a water flow restriction (likely) or grille (airflow) restriction (less likely). lower hose needs a spring/toss the stat for a quick test (wont hert the eng for just one time). belt tight (I'm sure you've checked it already (pump speed). rad IS unobstructed right? more rare is a rusted up block cooling passages or a slight combustion leak into the cooling system (an emissions testing station can stick the probe into the dead air space above the coolant & it'll show a reading if there are hydrocarbons present (combustion leak), in drive/ebrake on/foot on brake power brake it as a minor leak might need it to be pushed hard for it to show up. Holler how it turns out. water temp gauge you have is confirmed accurate right?
