Obviously, it's not good to leave your Mac at an extremely high temperature for a very long time, but fans turn on automatically when the temperature climbs up. In this case, fans shouldn't damage just because of the temperature (fans are on your computer to keep the Mac cold), but you must be careful and install iStat Menus to check the temperature > http://bjango.com/mac/istatmenus/
You're doing what some could call a burn-in run. Where you get everything hot and sustain that usage for long periods of time. The Mac can handle that, I have used older MBP's for the IT field and they had to process tons of data, they got hot, but I let them cool down at night.
The fans won't get damaged, its a solid-state motor, unless you stick something in the fan...
The thermal paste on the CPU/GPU may degrade quicker though. That is my one hesitation about dedicating this machine to that.
I should note, that the heat and the power consumption is going to take it's toll on your electric bill too.
85 watts * ~6 run hours per day = about $40 more on the bill.