Greetings
That's as good a specimen as you are ever likely to find, even the strop looks unused, a great find.
For what it's worth I have never been able to get a shave (even a bad one) from the NOS Valet blades, the original literature that came with the razors stated these blades should be stropped before first use. I have tried this and have failed miserably on every occasion, albeit although I have half a dozen Valet strops, not one is in anywhere near as good a condition as yours.
Although the Valet blades have a heavy coating of light oil on them I have heard arguments that because they are so old they might look fine but have degraded over the years because of microscopic rust, whether this is correct I have no idea.
You will, I have little little doubt, get a great shave with that razor using a Feather SE blade.
A little tip.. If you do try stropping, take it steady; if the blade fails to flip over at the end of the stroke you will cut the strop in two, as your strop is mint that would be a shame!
Regards
Dick.