Pegging the speedo, fun... but will it kill it? Options

[23e Heure]

I really fancy fitting a 120mph speedo to the car.
I have a spare '67 one from a 912.
Its needle has faded to a pinkish orange and the numbers are a really tasty old yellowed age.

(IMG:http://www.914world.com/bbs2/uploads_offsite/i13.photobucket.com-19057-1481244966.1.jpg)

My car has a 3.0 6 in it... So yes: the car will be capable of a significantly higher top speed, but on the road I should never get near that <ahem>.

But I am likely to use the car in germany on unrestricted routes, and also have plans to do a few track days.

I have googled and got confused about "pegging" mechanical speedos.
Research resuults range from "Exceed the top indicated speed and your speedo is broken forever"..
...through "You can exceed the max, but calibration will subsequently be buggered"...
...all the way to "Only some speedos don't like being max-ed, your one might just bounce at the top and then return to normal when your speed drops".

Can anyone give me accurate experienced advice, hopefully directly related to mechanical VDO speedos for early porsches?

If indeed exceeding the max is a no-no for old speedos, is there any mod available that acts as a protection mechanism?