871 celcius = 1600 Fahrenheit 800 celcius = 1472 Fahrenheit which is close to the ideal temp (820s to 830s), although 850 should start to set off a warning bells. your NEVER to exceed is 900 celcius 1652 Fahrenheit. I think your research will say the same (from all my research) I'd recommend finding gauges that support above 900 Celcius
Btw, my 'ideal temps' are probably different then tuning shops... since they are in the business of giving you maximum rwhp out the door... your engine longevity is not in their best interests. I'd recommend to tune for 800/810 daily. You could run 850+ for drag strips runs. I'd Tune for 760c for road courses.