It's pretty clear at this point that there is still a mix of B3 and G0 in the supply chain, so however fast Newegg is spinning through their stock is IMHO irrelevant.
The only ways that I have found to guarantee a G0 are as follows:
1) Purchase from a local retail chain where you can inspect product codes yourself, ~$330 + tax. ETA Now, if available.
2) Pre-order with TankGuys for a reservation fee of $5 (can cancel), $299 + shipping. ETA August 6th.
3) Pre-order with ClubIT (by telephone only), currently $296 but charged at the site price at delivery (free ship). ETA August 1st.
I ordered from ClubIT ... assuming the price stays stable I'm getting a guaranteed G0 with their fastest shipping option for $10 less than Newegg's price. Now, fingers crossed that it heads out the door August 1st!