i have similar ambient temps (outside the case where my radiator is) and i can run my 1.2 tbird at 1.47 and up the voltage from 1.75 to 1.85 and stay under 100 deg F.
the internal temp of my case stays around 85 to 87.
just to let you know in relation to what i was using before, i previously was using the stock AMD HSF that came with the 1.2 athlon, temps ran above 130 deg F under load.
also, i have both the 120mm fans and both the 80mm fans on my case/radiator hooked up to rheostats, and i always leave them running as slow as possible, making it virtually silent. (the hard drives and pump are the loudest things i can hear)
hope this helps
forgot to tell you what i'm using.
DD maze 2, Danner Mag 7, DD cooling cube
cooling the cpu
120mm fan on radiator (turned down via rheostat)
120mm fan on back of case drawing air over waterblock/video card (turned down via rheostat)
two 80mm fans on front of case sucking air out over 2 of my 3 ATA-100 HDD (both fans turned down via one rheostat)
one bay cooler from best buy cooling the third HDD