I have a stronglight 93 crank with a 52 outer chainring. I am trying to change the inner 45 to something smaller like a 40-42 or even smaller. I have a front simplex sj102a derailleur. 122bcd

I have a 1972 simplex prestige rear derailleur with either 13-24 or 14-24 6 speed freewheel (I can't remember). I am thinking of switching this to something with a lower low gear.

I'm hoping to make my gearing more conducive to the hills around here. What are limits on lowest gearing I can put on? 40/52 and a 13-26? Lower?