Re: biggest motor/ hp with shift kit?
What you mean by "standard" bike chain can vary depending on the type of bicycle and drivetrain it has.
Bicycles with derailleurs almost always use narrower chain than bicycles with internally geared hubs.
Also, bicycles with derailleurs have variable chain angles - the chain will not be straight in certain gears, which can pose a problem during high load.
All that said, a bicycle chain with good alignment shouldn't have a problem with a Pred 99.
If you're going to use an IGH, I'd worry more about whether that hub can take the power than if the chain can handle it.
You can easily run a heavy chain like 415H or 41 with an IGH.