We don't find many originals remaining after all these years since they were originally untreated paper stickers - unlike the current vinyl reproductions - which simply desolved in short order.
To construct a new one you will want a decal that uses black ink in the printing of the background layout and one where the horizontal and vertical lines meet or cross. Also don't use the reproduction that has the rounded corners.
Since we have no Marti reports to go by the guess of a completion date is solely that - a guess
as for the original style and type of markings for a spring 66 San Jose battery decal my best guess based on what I've seen would be that all of the information would be filled out by hand in either pencil or black ink (ball point pen) The first box to the left would be the specific gravity as measured (at that time) by a bulb (something like 12.5-12.7 would be typical IMHO) the date would be the month and day of month (no year) with a slash between the two in the center box. The final box to the right would be a part of initials belonging to the inspector.
Hope this helps - Other viewing this please do not use this as a guide for your specific car or decal unless your car matches EXACTLY