A few tips that might help in current version of DCS:
1.) You have a significant acceleration advantage over the 14, especially when the 14 gets slow, spreads wings (and possibly deploys flaps). So get the 14 slow, unload your jet to get speed for a brief few seconds, then start a climb. Keep nose up until you see the 14 drop its nose, now come over the top for a shot.
2.) If the 14 gets on your 6, don't just keep turning. Unload jet, fly straight (or nose down) to get speed and build the separation between you and the 14. Climb once you get to a comfortable speed (say, 550+), invert and split-S back into the 14 (I pull the brakes and idle the engine as I do this for more instantaneous turn and also to collapse my turn circle, as I start the split-S at around 550+ knots). Done right, this should help you even up the fight and recover your lost angles (or force an overshoot). You will have to experiment a bit with the distance to properly execute it. But extending and re-committing is crucial to the current f6 in terms of guns only BFM.
The current 16 is pretty bad in guns only BFM, but with a bit of persistence and know how, it can still win fights (sometimes).