I assume you are rich of peak EGT... So how far rich of peak are you?
If you can you can run LOP, and get cooler CHT and better FF or MPG (but slightly slower speed). LOP is not practical unless you have well balanced FI where all cylinders are close to each other in EGT. Too much EGT spread will cause rough running (leanest cylinder) while others might be near or at peak EGT. You also should have full 4 channel engine monitor to run LOP.
Absolute EGT is kind of useless because it is dependent on where the probe is. Need to know how far RICH of peak you are.
The cooler the CHT the better but 365F is pretty good. I would not go over 400F. But does 30F make a difference? Yes 1 gal an hour. Engine life? That is so dependent on many factors. No answer. What is your Oil Temp?
airguy said pull it back? I think he is talking mixture. Just FYI do not "pull it back" throttle wise. You are best at FULL THROTTLE... don't partially close the throttle. You can change RPM if you have constant speed prop (within Prop RPM/MP limits), but if you want to reduce power, fly higher (if winds are favorable or no worse). Lower density air will reduce your power.
Lycoming says.... normal operation, maintain the following recommended temperature
limits:
For maximum service life, maintain the following recommended limits for continuous cruise operation:
Engine power setting – 65% of rated or less.
Cylinder head temperatures – 400˚ F. or below. (that is my limit but 420F for short period is OK hot day climb, but I would not want to cruise 400F constant if able.)
Oil temperature – 165˚ F. – 220˚ F. (you don't want to run too cool, 185˚ F indicated is ideal min. That means oil in head is above 212 and boils off mosture.)
Lyc also talks of 100F RICH OF PEAK... That is pretty rich, but it sure does cool the engine down (and waste fuel)ppp... 50F rich of peak or smooth operation is good if all temps are well in the normal range. Also leaning applies only if you are below 75% power.
Great video on LOP operations.
https://www.youtube.com/watch?v=h3bATVXMHQg