Finder identifies smb://127.0.0.1 as a local filesystem and refuses to mount port 445 even if you've set up an SSH tunnel using -L 445:localhost:445
The solution is to alias your lo0 interface to 127.0.0.2 and Finder doesn't see this as a local address.
sudo ifconfig lo0 127.0.0.2 alias up
Create the ssh tunnel and map to your Samba / CIFS server
ssh user@remote -L 127.0.0.2:445:smbhost:445
Now you can open the share in Finder
smb://user@127.0.0.2