yo 39, former JB dora man here...
bring that convergence in. alot.
i set mine to about 250 for both guns.
also with the 190, if you are closing as fast as you say, you should get to 300 or closer before shooting, then bank out of the collision.
either way, learning to shoot the Dora is different than most planes i flew, a good 60% or more were high speed high deflection shots, where the enemy is below my view anyway. when you can not see the enemy in those fast turns you just have to practice making the shots. it will take time, for some years to do the deflection shot.