I have an early FN Model 1906 Vest Pocket Pistol.  This is a WWII dring back from my father-in-law.  SN. 50,420.

The overall condition is very good with the exception of the barrel (severely corroded) and the firing pin, which is broken. I was able to replace the barrel with a new manufacture barrel.  The firing pin, on the other hand, is another matter.  I purchased a reproduction firing pin from Numrich but the sear does not pick it up.  It is shorter than the original ye .3" which may be the problem.  I don't know.

I would like to keep it as original as I can and still have a shooter.  Any suggestions as to where I might be able to find an original.  I have searched the usual sites without success.

I was under the impression that a Colt 1908 vest pocket firing pin will work. I used the Colt spring kit from Wolff in my FN 1906 and it worked great. Look for a cheap used pin on eBay and ask the seller to carefully measure it or if cheap enough give it a try.
ETA: come to think of it I put a Colt extractor in it I got off eBay too. Issue ended up being old weak springs but I left the Colt extractor in and it runs like a top.

I stay away from reproduction parts. Also, make sure the pin they gave you is not for a Baby Browning. I can measure my 1906 pin against my Baby Browning when I get home to see if it’s off by what you describe if you’d like.