With enough work fixing induction leaks, especially the carb heat box, it is possible to run our O-360s LOP; mine is often good to about 25°LOP now. But I still run 50 ROP. the trip to the Summit was right at 50°ROP; initially 7500 msl, 21"/2500 before clibing to 9500 and running (WOT - a tad) / 2500. Both peaked right at 1500, so I pushed the red lever for 1450. ASI was hovering between 140-145 mph, a little higher at 9500 than at 7500.
I've been doing this the last 700 hours; the plane had ~180 on the engine when I bought it, it's now about 860, and compressions have never fallen below 75 on any cylinder and are often 76-78 on all four. The MAPA PPP saved me lots of page flipping, as I just make sure MP + RPM <= 46 instead of worrying about % power. But I verified things for a year or so before figuring out some basic settings that cover most of my flying (whuch also simplifies IFR flying with step changes up and down).
The important part of EGT is not the absolute number, but the distance from peak.