There are copies of this map posted on line many places, but if you go to the original Dave Arneson site called Castle Blackmoor found in the Internet Archive at Castle Blackmoor and in the left hand side menu click on Blackmoor Campaign you will be able to download the following items which Dave Arneson was personally making avalable to fans.
The original Campaign World!Blackmoor
Click of the map to the side for a downloadable map for printing on a 8x11 sheet at 300 dpi.
Click on Blackmoor campaign book image to download the PDF version of the original books.
(That is Blackmoor Supplement I of D&D)