I got the x60 and OCed to 4.2 and getting temps around 73°C using Prime.
I guess yours will be the same.
Always depending on your chip of course.
"Dangerous" is pretty subjective when it comes to overclocking...especially Haswell.
Let me put it like this: Your CPU will throttle at 105°C. Most overclockers try to stay under 80°C or in the low 80s at max.