Use a RCA stereo patch to the DR-670's R&L 'Line-Out' to the BR-1180's R&L 'Line-In, arm two tracks and record.
The BR-1180 drums will generate a MIDI clock if you use one of BR-1180's drum pattern. The DR-670's drums should receive on MIDI Ch 10, I have a DR-5 and it receives on Ch 10. Use a MIDI patch cord, with the above RCA patch cord config, and when you press play on the BR-1180, the DR-670 will start playing.