I'm with you all the way, no C+V is complete without a Silca, especially when its a paint to match.... this one looks great.
This one looks to be a bit short, was it on the ST to begin with?
You might be able to JB Weld a braze on nib if you make a bare spot for it, I would/might drill a small hole in the nib and HT

and use a pin with JB but the pump has to be well spring loaded to stay in place.
Proceed with caution and good luck.
I would also consider these for the bottle cage.
https://www.universalcycles.com/shop....php?id=103403