Finding bottom edge of the left diagonal bevel (x=340 to 577):
x=350: edge at y=660 (v0=210, diff0=101, v1=208)
x=370: edge at y=660 (v0=218, diff0=108, v1=219)
x=390: edge at y=660 (v0=232, diff0=107, v1=233)
x=410: edge at y=485 (v0=98, diff0=64, v1=36)
x=430: edge at y=504 (v0=61, diff0=50, v1=32)
x=450: edge at y=522 (v0=129, diff0=49, v1=48)
x=470: edge at y=543 (v0=52, diff0=34, v1=44)
x=490: edge at y=560 (v0=57, diff0=38, v1=39)
x=510: edge at y=578 (v0=78, diff0=27, v1=19)
x=530: edge at y=596 (v0=120, diff0=52, v1=16)
x=550: edge at y=615 (v0=65, diff0=51, v1=30)
x=570: edge at y=633 (v0=131, diff0=59, v1=26)