Chainline setup - is it really as simple as...
 

The crankset I want to use on a project bike is supposed to give a 45mm chainline with a 103mm BB. The IGH rear hub (130mm OLN) gives a 50mm chainline. Basically, I need to move the chainring out 5mm.

Is it really as simple as buying a 113mm BB? From some of the other threads I've read this just seems to be too simple.

But, maybe it really is.

I thought that I read some BB are not symmetrical, but I cannot find that information now that I need it. If a 113mm BB is symmetrical, then I think that's all I need to find and the chainline should be just right.

yes it is that simple

as long as your current bb is symmetrical
and your cranks are designed for a symmetrical bb
then you just need a 10mm longer bb

Yes, you remembered to double your desired delta because it will be for both sides. Although it makes more sense to me if every BB had the same width out the left and all the variability went out to the drive side. But I guess that would mess up Q-factors.

as the others have noted, 10mm does the trick as long as it's another 5mm on both sides.

That's really the key, 5mm (or close to that, since 1-2mm off is OK) more on the right.