I found a person who sells reproduction vintage State Inspection Stickers and other vintage auto stickers. Looks like he has most States.
Bob Hoyts Classic Inspection Stickers | Add a Final Touch to your Restoration!
I picked up a Texas 1965 and 1973 sticker.
Back of Sticker
I put the 73 on my Car and found out that you shouldn’t fill out the back of the sticker with a permanent marker as it will bleed through. The word August bleed through above the number 8. I then changed to a ball point pen and was fine.
$25 per sticker.