See here:
So with your bridgeline specifying [your ip]:8080
etc. and ServerTransportListenAddr obfs4 0.0.0.0:8080
specified in your config then clients will connect on the port specified. Like this:
Aug 01 09:31:16.275 [notice] Opening Socks listener on 127.0.0.1:9050
Aug 01 09:31:16.276 [notice] Opened Socks listener connection (ready) on 127.0.0.1:9050
Aug 01 09:31:16.276 [notice] Opening Control listener on 127.0.0.1:9051
Aug 01 09:31:16.276 [notice] Opened Control listener connection (ready) on 127.0.0.1:9051
Aug 01 09:31:16.276 [notice] Opening OR listener on 127.0.0.1:0
Aug 01 09:31:16.276 [notice] OR listener listening on port 58225.
Aug 01 09:31:16.276 [notice] Opened OR listener connection (ready) on 127.0.0.1:58225
Aug 01 09:31:16.276 [notice] Opening Extended OR listener on 127.0.0.1:0
Aug 01 09:31:16.276 [notice] Extended OR listener listening on port 58226.
Aug 01 09:31:16.276 [notice] Opened Extended OR listener connection (ready) on 127.0.0.1:58226