The door opens up with a hinge on the top edge so piping above it will definitely be a challenge. It can be turned any of three ways but if it opens on the supply line side it will require 90* Els to clear the door as it opens since it will swing right into the pipe if you go straight up. Hope this helps, let us know if you need more info, perhaps you could post a pic of your install so we can see if there are issues.
If I remember correctly from a few months back with the easy clean out completely swung open to the vertical position the handle side of the door is about 25” from the top base of the boiler but I’ll check the measurements and post back if you need.
My clean out is mounted as factory installed as are most other installs I have viewed in the forum.