54ed
There is no remedy for the problem of estimating the correct lead angle when the issue is visibility over the nose. Other than chopping off the nose! :-)
If we assume that the respective fighter velocities are going to be somewhat similar, then any high angle deflection shot is going to produce a lead angle that may well be outside the physical viewing boundaries of the sight (when the attacker is in-plane with the target).
I deliberately use a bunch of qualifiers when I talk about this subject because the subject is....well...subjective. There is no way to find a 'one size fits all' gunnery solution in this highly dynamic situation ('dynamic' in this sense means a lot of things are changing fast!!).
Projectile ballistics do make a measurable impact on the question. However, it's not a matter of a particular weapon shooting 'straighter'. Instead, it's a function of muzzle velocities. Slow muzzle velocities produce a longer time of flight for a given firing range, and this results in the lead angle being larger than would otherwise be the case.
Additionally, the selected harmonization range (known as 'convergence' in AH) deals only in azimuth corrections, not in elevation corrections. As such, the convergence settings only affects bullet density at a particular range and have nothing to do with lead requirements. As long as we expect that the relative fighter velocities are somewhat similar, then the required lead angle in mils (an angular unit of measurement) stays relatively constant over the typical range of firing opportunities in high angle off situations.
Therefore, convergence has an effect on when you should pull the trigger in range...but has little to no effect on the required lead angle.
In any fighter, it is possible to 'track on the beam', in other words conventionally track in a high angle deflection situation. The extent to which you may do so is a function of two things...visibility over the nose, and the target velocity.
Finally...this is only a sim and may or may not be programmed correctly with regard to real world ballistics. My experience with it is that it is 'close enough'.
But this means that the target may well be below your nose in many high G and/or high angle off situations.
Andy