If the gun is an original target-sighted gun, you should drop everything and go
back right now and get it. Front sight blades are around - not growing on trees, but
around. A factory letter might specify what the front sight blade was, if special
ordered. If it wasn't a special blade, then it would have been the standard blade of
the period. A good machinist and/or gunsmith can always make a front sight blade.

If you do go back, get some pictures of the gun.

Mike Priwer