Not what i was guessing. Hats off to you on your successes and talents.
If I were in your position, I would take the three million offer. This is assuming you would be able to back out if things became intolerable.
If you are looking to spend $300,000 a year, 8 million is not enough of a nest egg at your age, in my opinion. If most of this is in 401K accounts, you may have to draw close to $400,000 a year to clear $300,000 after taxes. If most of this is in taxable accounts, I'm not sure how much you would have to draw down, it depends on how much of that money is capital gains. Also, capital gains and dividend taxes might very well be much higher a few years from now. There are already proposals to increase the tax rates on long-term capital gains and dividends, and it would not be surprising at all if this happens, given the current political climate.
Anyway, the point is, you would start out with a spend rate of possibly around 5%. This is too high at your age. If you took the three million offer, presumably you would clear around 2 million after taxes, which would bring your nest egg up to 10 million and you would be looking at around a 4% draw rate, possibly. This is much better. Even then, you should be prepared to cut back your spend rate if the first few years go poorly for you.
So I know it sounds ridiculous to say a 8 million is too little to retire on, but if you want to spend $300,000 a year, it really is not enough. Back to work! Or be prepared for the real possibility that you may have to significantly cut back your spend rate.