That oil pump issue might be a stuck bypass valve: this is pretty common on the K4-5 era engines when Honda changed their molds. This also wasn't the first time: the 'new factory' K1 bikes also started out with the first of these leakers I remember seeing. What happened with the K1 bikes was: the hole where the little piston moves in-out with pump pressure, to hold oil in the pump and in the oil filter separate when shut off, would warp oval-ish in the sand-mold pump bodies, making the piston just barely stick open. In the K4-5 situation it happened near the transition from the K4 to the K5 engines when something must have happened to one (or more?) of the pump molds, which left a small ridge inside the tunnel where the piston's seal rests (these were not bored to finish). After some years of use, these will distort slightly and then the O-ring sticks, holding it slightly open and lowering the oil PSI about 15 (to 30-ish PSI at 4000 RPM with hot 20w50 oil). The 'cure' for the latter one is to remove the piston, gently file the ridge away with a round-profile file (it's on the top of the tunnel) and install a new O-ring. The K1 pumps usually just had to be changed out, or the hole rebored (tedious) to round and a new O-ring installed.
