I would suggest the 180 if you plan to drive the car (ie. not drag strip only).

Keeping water temp at least 180 helps reduce bore wear from condensing fuel. Also keeps temps steadier when running so the tuneup (mostly timing) can be dialed in correctly. If you run a 160 temp will be near 160 sometimes... and probably warm up to 180-200 sometimes under load in warm weather. If timing is set to avoid ping at 160 it may ping at 180-200. Similar effect on fuel mix and jetting. Actual temp under heat and load will depend on cooling system performance... a 180 stat should be fully open by about 185 degrees.