Well, personally, I don't experience a "high" from any benzodiazepine. Period. I've tried a variety of them at a variety of doses. All I've found is that higher doses cause great disinhibition and increased sedation, but I really don't experience any euphoria whatsoever (when I refer to getting "high" it implies euphoria).
High doses, for me, merely provide effects not unlike those of having a few too many drinks. The difference, however, is that I don't experience the vertigo and nausea that is associated with alcohol. In addition, large doses of benzos provide more relaxation and less agitation than drinking a large volume of alcohol.
As for temazepam specifically, I've taken 200mg (they are produced in 10mg pills where I live) of the stuff in one go, without a tolerance. I didn't even pass out; in fact, I was functioning throughout the day, albeit in a bit of a haze...
So, assuming you're not on any other CNS depressants, a dose such as the above-mentioned won't send you to the ER. But perhaps to err on the side of caution, try 120mg first.