Agree with Dirk. It's hard to tell with a carbureted engine. In fact, consistent LOP across all cylinders is hard to achieve with a carbureted engine.
When you lean until roughness sets in, then enrich until the roughness disappears, you have most likely achieved the situation where one or two cylinders are so LOP so that they're about to stop producing power (that's where the roughness came from) and the rest is peak or ROP. Maybe even well ROP.
Without per-cylinder instrumentation (EGT, CHT) and per-cylinder mixture control (for instance with balanced fuel injectors like GAMI makes) this is really the best you can hope to achieve.
I don't agree with IF2. If you are above 7000 feet and your engine temps have stabilized after the climb, going WOT and leaning should not harm the engine. Unless it's turbocharged.