The J2B (or is it a J2BD? I forget) in the 1980 PA31-325Navajo** I operate specifies 43" nominal MAP/2575/full rich for max power, then set 38"/2400/ US 28-32GPH for climb power. I never use less than US 32GPH for climb, erring on richer than that to ensure never leaner. Even so, I'm now tending towards full rich even for climb power.
For the last 7 or 8 years I've run it LOP for cruise. Nearly always 33"/2200 RPM /27 US GPH which gives a TAS of 170kts +- 2 kts at A120.
**It's a Mike Jones 'Lock & Key' Colemill Panther Navajo, with 350HP engines. Nicest Navajo I've ever flown.