Lately I've been using the Nelson plug, 20% Rocket Science fuel with a Novarossi carb from my NS12 (with the removable venturi). You indicated it's bogging slightly on acceleration and I assume it's fine through the mid and high range. So my guess for the solution to your flame out problem is to richen the bottom end needle a little. Try richening the bottom 1/2 to 1 hr at a time until the problem goes away. I've noticed that the PS12 responds well to small needle changes once you're close to optimum tune. I used to change them a 1/4 turn at a time and think I was tuning myself out by doing that. Try the 'pinch the fuel tube test' and count how long the engine takes to stall. Pinch about 3 inches back from the carb, mine usually takes 1.5-2sec. to stall. In TX I have to run a few hrs richer bottom end than I did in Cali. I'm curious, where do you live?
The design of the engine dissipates heat so well, I think the temps are masking the mixture just a little. That's probably why you're not seeing 280-300 like a Nova might with those needle settings. Also keep in mind that with the good dissipation, comes taking a little longer than normal to build the heat. I try to run my engine for 2min. on the track before I try to maximize the tuning. I like to let the engine warm up to race temp before I try to judge mixture or check temps.