I am not to sure about raising your seat/head psoition, I would rather suggest setting up a key/button for viewing over or around the nose. I leave peoples convergence to their personal preference.I too adjust almost ever plane to 350, except when having cannons and MG's combined, then I will set the cannon 25 to 50 further out so they fall in at same convergence point as the MG's...
back to the raising your seat/head position......this itself can be a personal preference as well. depending on the plane I will move myself forward or backwards in the seat so that in my default forward view, I can see all gauges that are most important...and you also gain more "SA" the further back in the seat you are, allowing you the ability to get better viewing from forward right and forward left..
going offline or in the TA and turning on the lead computing sight, will help you as far as learning how much you need to lead an opponent when shooting from different angle.......wether it be 250 yrads out, 300, 400, 500, 600 , 800.this will show you how much you need to lead them , and will give you a mental picture to draw upon when flying in other arenas......