That is something that Sergio Sismondo can do .
Since he is not with us any more , then I can do it for you if you donate to this chat board . You can become a supporter ,read the side bar .
To save time, here is what you need to know for the difference between the thick and thin overprint .

Chesham 85 --- Now you can say you seen and know the difference . Also think of being a supporter to see more stuff you never seen too !