I wouldn't worry about that at all. "Very hot to touch" could just mean 60 C. 70 C would be scalding, really. Anyway, such temps won't hurt your chipset. Chipset chips (hurr durr) are quite resilient to hi temps.
BTW, have you measured how hot it actually gets? Speedfan, AIDA64, HWINFO?
Anyway, for starters I'd simply ditch the flimsy plastic bolts with puny springs and instead use a proper bolt + nut assembly. Pressure is the key. If SPCR's CPU cooler tests teach us anything, is that pressure does matter.
While you're at it you could also remove the factory gop with some decent TIM.
The NB and SB (it's 775, baby) chips in my HTPC (or rather: my MKV-player-PC :E ) get hot as hell. Can only keep the finger there for 1-2 sec. Anyway, it's been running like that for several years now and I never had any problems with it. Well, truth be told, the little PC is usually on for 2-3 hrs at a time, no longer. Still, it's very weakly ventilated, with only one 12cm fan in the PSU, running at 600-700 RPM. Also, the CPU cooler fan will not start at all times (I like to live dangerously...). I once applied 2 small 40mm Scythe fans @ 5V to both heatsinks. Just for kicks. Well, the temps went down, there was no increase in noise, but also it didn't change anything in terms of reliability. Next time I was messing with the PC I took them out and stashed away.