At power settings above 65% you need to be concerned about running too
lean, thus too hot. With monitoring all 6 cylinders it should be
possible to run 50 to 100 rich of peak at these high power settings.
You will have to lean until you hit peak, then richen. Use this EGT as
a guide. I would use 100 degrees rich of peak on power settings above
75%. This is on your hottest cylinder.

At power settings below 65%, you do not need to worry about running too
lean, so just lean until it runs rough and richen slightly. Note the
EGT on the hottest cylinder and use this EGT all the time.

Most of us pilots lean to a specific EGT. I use 1350, but I only have
one probe on one cylinder. The exact temperature varies with probe
installation. On my carb Lycoming 360, 1350 is all the way lean at 50%
power and maybe 100 degrees rich of peak at 75% power and 50 degrees
rich at 65% power. I have an engine that is well over TBO and still
going strong using this technique. One thing you can do is lean all the
way to roughness while at full throttle at 10,000' then richen till
smooth. Note the EGT and use this as a target setting at all power
settings. This will give you rich of peak at higher power settings and
all the way lean at 50% power.

You will read articles about running lean of peak, but most of this
only applies to engines with fuel injection and GAMI injectors. They
run these engines lean of peak at high power settings to help cooling
and fuel economy. It usually wont work with carbureted engines as you
will have uneven air and fuel distribution.

Lean on the ground for taxi as much as possible. Lean for takeoff at
airports above 3000'. Don't go full rich on landing unless landing at
airports below 3000'. Leaning for takeoff involves doing a runup and
leaning until you get an rpm drop, then richen 3 half turns on the
mixture knob. This works well. For landing, just lean to the takeoff
setting judging on how far out the mixture knob was set on takeoff.
This is all for airports above 3000'.

Hope that helps.