I might need to specify a 56.3° elbow. (to match an 8:12 roof pitch)
If you can get (2) 30s and are OK with a small out of plane offset, you can do that easily:
Use the (2) 30s to make a 60, put it on your plumb conduit and point it along the roof gradient. The angle will be too shallow and the conduit would hit the roof. Now rotate the elbow-elbow joint so the uphill end is as a steeper angle (less bend off plumb), while rotating the elbow-conduit joint so that the uphill end is still pointing along the roof gradient. Shouldn't take much adjusting to get from 60 degrees to 56.3 degrees.
You could obviously do that with a 45 and a 22.5 instead, but it will take more adjusting and give you a larger out of plane offset.
Obviously not as pretty or elegant as a custom bend, but quite simple and perhaps good enough for a roof.
Cheers, Wayne