Please keep in mind that the original map is saved with 72 ppi. So, before you print it, change that value to at least 200 ppi. Better try 300 ppi
When the text is still bad readable, cut the original map in four pieces, overwrite the text with any readable font in a readable colour (see attachment) and print it. Tape the four parts together and you'll end wit a huge map app 10 feet high and 8 feet wide.
Good Luck
Aad
BTW, for those who don't know ppi stands for Pixels Per Inch