Lugging an engine is a lot easier to do if you have drive wheels hooked up on pavement. Sure, you can raise the MAP by pulling prop, but you can't pull the RPM low enough to really lug the thing like you could an old 6cyl Rambler station wagon on a hill. Goes straight to detonation. If you can't keep it from cackling, you have to downshift. If you don't downshift or let up, that's when the real lugging begins. You could drag it right down to where it stalls. And yeah it might throw a rod. Hard to drag the RPM down that low with a prop.
The governor downshifts for us. It changes pitch to shed load so the prop will speed up. If you push throttle, pull the prop to the stop, (go around maybe? should be pushing the prop for climb) and manage somehow to load the prop so much that the blades are on the stops and hold it there, you'll either overheat (and the more than probable onset of detonation), or the prop will stall and the engine will speed up, or the wing will stall. The pilot already has.
We, at least I, don't normally operate anything like that. Climb at higher RPM, more horsepower there = better ROC, and cruise it lower = better efficiency. Lean, when and to the extent, appropriate. I cruise well lean of peak and WOT, even down low, as my injectors are tuned for it and I regard CHTs as a primary instrument for setting power. If my cylinders start trending upwards towards my 400* personal redline, I'll lean more (or get well ROP), push nose over for better cooling, open cowl flaps, and/or pull some throttle, that being my last move.
Dan is right as usual - avoid detonation. Always monitor CHTs at higher power settings, ROP or LOP, and set a conservative alarm temp. If it isn't getting hot it isn't detonating is a pretty good rule of thumb, and always start your experimenting at much higher altitudes than where you can make 75%.
If you don't have CHTs for all cylinders don't try to operate lean of peak at high MAP.
YMMV
Ed Holyoke