Look... They told you what you're going to hear...
What motherboard do you have? What cooler are you using? I run 4.8GHz and I've never hit 75C. That's because I have a custom liquid cooled loop...
For 4.3GHz, you probably won't need more than 1.25V. I'd say start there, and see if you're stable. If you are, back it down until you're not. Then bump it back up 0.01V and make super sure you're stable. You'll find the sweet spot for your specific chip, mobo, etc.
Best of luck