Since we know we were mode-matched fairly well into the 180 µm waist of the silica/tantala cavity (>93% visibility), I asked alm to propagate this waist backward through the lenses in order to find a seed waist. It reports a waist of 161 µm at z = −1373 mm.
I asked alm for a new configuration using the same two lenses. The best configuration (mode overlap = 1) is as follows:
So we should move lens 1 back by 32 mm (=1.3″), and move lens 2 back by the same amount.