Worse case scenario ... they leak. Source two better ones, and fit all your nice new bits into them. But, I'll be surprised if they don't hold pressure.
If you're changing the front end (with what, you don't say), why stay with 41mm stanchions? Most RWU's are 43mm, Z9's are 46! Find a decent, complete front end, and put your spare stem in that.
Measured my pin. It's 312mm from under the head to end of thread. So, OK to use with rearsets, but not long enough for std. footrest plates! @gsxBe interested to know dimms. of YZF450 one thonugh.