It’s not about running mad power , but it’s not that much more effort to do a few improvements and put the head back to better than new .
Some things have to be done anyway , like crack checking and measuring any warp in the head ,cleaning .
So if the head is off anyway and valve seat are to be lapped , why not reangle seats , cc the chambers , check cams are parallel , new valves and guides and port .
Yes it’s more cash , but the head is the heart of the engine where all the action happens ,the heat and pressure are all created here .
This effects the whole engine in some way or another ,not just power but longevity.
The extra power is a side effect of that extra longevity, due to better heat paths and flow .
Aluminium melts around 650 C ,the combustion temp is way above this (but only intermittent ) hence the need for cooling paths - the better they are the lower the head temp peak - things like valve seat width form the heat path along with guides ,valves , plug threads and so on - the better the heat path more heat is transferred to the water /oil - less stress all around on gaskets ,pistons ,rings -and the head - a longer lasting engine .