What is the usr/local default chmod?
The default permissions/usr:grp/attr/SIP since 10.11.3 are 755, root:wheel, –, –:

ls -laOe@ /usr/local
total 0
drwxr-xr-x   4 root  wheel  -                 136 29 Mai 20:37 . # ⇦ /usr/local
drwxr-xr-x@ 13 root  wheel  restricted,hidden 442 29 Mai 20:31 ..
    com.apple.FinderInfo     32 
    com.apple.rootless    0 
drwxr-xr-x   5 root  wheel  -                 170 29 Mai 20:37 bin
drwxr-xr-x   3 root  wheel  -                 102 29 Mai 20:37 share