RedBull,
Convergence doesn't matter with the MK108 Motor Kannon. The secret you want to the MK108 in the K4 is to simply become a master K4 ACM practitioner. Then you cannot miss when you set your con up to fail inside of 100 yards. The Ta152 for whatever code programing reason shoots flatter inside of 300. So set your MK108 to 200 and your MG151\20 250-300 and pull the trigger 200 and closer.
I've noticed the players who land consistant high kill strings in the K4 and 152 are also highly accomplished ACM pilots in both fighters.
Just remember that dispersion pattern from the real MK108 testing and my in game testing before shooting at anything smaller than a bomber past about 200. Or keep a hugh perk bank to fly a 262 all the time. The four overlapping dispersion patterns increase your hit probability out to 400 by 4x. The germans understood this and set the upper 2 to H\Vconv 400m and lower 2 to H\Vconv 500m.
Get a muppet and go learn K4 ACM in the DA. There is no secret convergence involved.