Purchase prospect

[WHO]

I am contemplating the purchase of a PH grade Parker. According to the serialization book, this gun came with double triggers and one set of barrels in 1922. It now has a second set of barrels which have a 1936 Remington repair code stamped on them. The gun also has a single selective trigger installed. Attached are a few photos of the gun. One photo shows the SST. Is there any doubt this is a Parker trigger? The gun also has the problem of the top lever always returning to center when the barrels are opened or removed from the frame. Is this a minor issue that a qualified gunsmith can easily repair or could this be a major repair?