The M8137 valves you are interested in are ones I own, where all retained Valves from purchases made, have all been tested and are comfortably within factory specification.
I did not achieve this simply by purchasing valves and relying on the measurements provided by vendors. I only proceeded with purchases when sellers agreed to the testing criteria outlined in my previous post. For clarity, all measurements were taken using a calibrated AVO valve tester.
Over several months, I purchased more than 12 valves sold as matched pairs. The advertisements included attractive measurement data for each valve and half valve section.
However, when I had the valves tested, some of the valves' actual measurements differed significantly from those stated in the ad.
Following a number of returns and further purchases, I eventually assembled a set of six valves that are effectively interchangeable, closely matched, and all meet or exceed factory specifications on both half valve measurements.
Note: A valve specialist who is visited to carry out independent testing, explained that most valves will still function and produce sound even when their performance is well below factory specifications. He also noted that many valve owners do not know their valve's condition regarding factory spec and continue to use low spec valves without concern.
The advice I received was that a valve's published test results shown in an ad are just as important as the photographs used for the ad showing the valve's physical condition. A buyer may decide not to purchase a valve that appears to be in poor condition, and they may also reasonably question the asking price if independent testing shows that the valve's actual performance differs materially from the specifications advertised. In my arrangements, I do not negotiate the asking price when the spec is proven to be concerning; I already reserve the right to return a valve.