Anthony,
Many thanks, I had not heard of a VINTEM either so had a search and found this....[in a 1864 travel book]

https://books.google.co.uk/books?id=6dJDAAAAYAAJ&pg=PR13&lpg=PR13&dq=portuguese+vintem&source=bl&ots=4pFZwVk3R7&sig=vqYxqMTdclFBgiKsprmbeq1WiNU&hl=en&sa=X&ved=0ahUKEwiN7ZGfkLLaAhXr44MKHR1zDOkQ6AEIdjAO#v=onepage&q=portuguese%20vintem&f=false

1 Dollar [Milrei] was a 1000 Reis silver coin.

Paul