There's a chapter "critical speeds" in the given documents from the Avsim file where you can read a wide range of data exceeding the shown placard (which still is a good source).
I don't know exactly the values for a correct calculation of the approach speeds then but I usually go with the always right 1.3 multiplier.

So if e. g. the aircraft has a given stall speed of 100 knots (which is an example of course) at the given weight and flap setting, multiply this critical speed with 1.3 and you have the save margin of +30.
You therefor aim towards 130 knots.
Winds might alter this value additionally.

As Airliners usually don't land like small General Aviation planes (big flare, near stall speed touchdown) but are flown onto the runway, this will give you a nice approach with a slow retarding throttle just before touchdown and very small pitch changes.
No need to get close to stall here.

I think we agree that those speeds and additional data would be best to come with the installer of the precious 707.
As seen on some other devs planes, a kneebord showing an overview of the most commonly used values would be fine too.
Maybe someone puts that into the wishes section of these forums.

I'm not good at handling html files but there might be a user around who collects some data and puts it into a kneebord file for everyone to load.
Friendly captains surely would appreciate this  :)