Is inequality good for growth?
It depends upon how and why the inequality exists.  Equality can also be bad for growth.

In the old Soviet system, most people were approximately equal and this was done by the use of police power.  It did permit rapid industrialization but then stagnated.  Not all innovation was good either.  Look at the Trabant.  An amazing vehicle.  Watch https://www.youtube.com/watch?v=No1-4GsQa-g

The US used to be very flexible.  That was good for growth.  If you were born poor, then you could become rich.  If you were born rich, then you could become poor.

Some income inequality is due to changes in technology and required education.  Some are due to legal changes that transfer resources from ordinary people to the rich.  It is now very difficult to become poor if you are rich and to become rich if you are poor.  That damages the incentives to build a business to grow the system.

Inequality is neither good nor bad, by itself.  It is a consequence of something else.  It is smoke; it is not fire.

There are several papers by Peter Temin that are very good on the topic, but he has quite a few and I don't know exactly what you are searching for or have already read.