Model it laying down flat on the ground with a complex profile wall.
You'll get the profile you want, you can curve the wall to suit the arch and the top will mitre.
Then save as a morph, rotate and move into position.
As a morph you can then edit it further if you need.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11