Simulation of APCBC shell from the 128mm gun of Pzkpfw VIII Maus hitting hull front armor of KV-1.
Pzgr 43 ( APCBCHE shell) at 860 m/s
vs
75mm (262BHN) RHA at 71 deg.
(angle of fall ~ 1,5°, I mentioned that both vehicles are standing on level ground, although at such distances a difference of 2-3 m would be normal, anyway it is not something that noticeably affects the angle of impact)
KwK 44 gun muzzle velocity - 920m/s (860 m/s at 0.8 km)
calculation time ~130h