When I worked at a Peugeot/Nishiki dealership in the early 1970s, most customers wanted a lower bottom gear on their P*-10, all of which came back then with 14-15-17-19-21 freewheels. Standard procedure was to replace the freewheel with a 14-28. The best solution was also to replace the 45T inner ring with a 40, since 52-40 / 14-17-20-24-28 makes a superb 1.5-step ratio progression and was standard on most of the UO-8s and AO-8s of that era, although we also saw some 52-36 / 14-26 and other combos on them. The stock Simplex derailleurs had no trouble handling 28T in back.