I don't think the Yak-7B has the performance to just arbitrarily break off from the Ki-43 and A6M3. It is faster, and if it starts with the E advantage can be flown smartly and retain the ability to break off if the fight starts to go against it, but if the Japanese fighter starts with the E advantage the Yak-7B is not in a good place as its speed advantage isn't so high as to allow nearly effortless disengagement as, say, an La-7 could.
We need to have a fair comparison... Co-Altitude. I've killed a Me 262 with an SBD, catching him low and slow. Clearly, one cannot analyse performance unless there is a baseline as a reliable reference.
Co-Altitude, an A6M3 or Ki-43-II can't do much. The Yak is far faster at all altitudes, especially the deck to 12k. I've flown hundreds of duels, Zero vs just about everything. The Yak's speed advantage is insurmountable if the Yak pilot is half-way smart. The Yak pilot can literally toy with the Zeke or Oscar. He cannot turn with them, he cannot outclimb them in a max rate climb. He can, however, pick and choose how and when he engages. Both of the Japanese fighters cannot keep up in a high-speed climb. Set your climb rate to 2k/min and simply leave... Split-s and wave goodbye. Disengage at will. However, beating them is not difficult either. Merge at 5k. Yak is 40 mph faster. As they pass, 95% of the time the Zero/Ki-43 will do a hard reverse, burning of what little speed it had. The Yak extends out 1k to 2k and goes pure vertical. The Yak rolls out 2k to 3k above the enemy. The Yak builds his E a bit in a slight climb and then rolls in. Rinse and repeat as required. The Japanese fighters are totally defensive, and sooner or later, will get popped.