Jeff did they do the stamp in ink or white paint as I've never seen white ink?Also what size was letters etc?
Since it has held up this long my best guess is paint though paint would cause issues with stamps over time - and not very long given the volumn of horns marked. At the same time paint tends to be pushed off of the top of the digits on a stamp and pool between if pressed too hard againist the surface - not something I have observed on these parts. So IMHO the jury is still out. Either will work today in reporducing the look. Yes you can get ink pads and white ink for the pads - just not real easy. I have one for my usage
The font like most of these is no longer in circulation and don't believe ever converted to a digital form for use in computer applications. This is very common and the reason I redraw every letter on every stamp I make by hand. - Have hundreds
There are some modern fonts that will get by I would suspect - but depending on the specific letter or number one might notice a difference
Measuring my stamps (haven't done a 64 dated one) the compressed height appears to be 3/8". Remember you need to figure in the compression ratio into the stamp or it will end up being too large if you simply copy the finished stamp on a part and make your hand stamp from that - seen it allot
Hope this helps