The thing is however that the TSO-540 is connected the a constant speed propeller in general and therefore when you lean past best power to best economy, the power will reduce and the blade angle will decrease to keep 2400 Rpm.
The question however was about a fixed propeller. Do you have to adjust to 2400 Rpm again after leaning as power goes down at best economy, therefore rpm decreases a bit?
In general the engines are set to operate at a mixture that is too rich. So what happens according to me is that as you lean to best power Rpm increases a bit (20-30 Rpm i'm guessing) and speed increases a few knots, then as you continue to lean to best economy Rpm goes down a bit again and will be roughly around to initial Rpm again.
So in my view the question is not do you have to increase Rpm at best economy but do you have to decraese Rpm at best power?
I would not change the throttle position after leaning.
Bart