You can convert a Peugeot pretty cheaply as a number 5 square tapered axle can be used to replace the cottered axle... just as long as your bb cups are in good condition.

My '62 Peugeot got an SR / Peugeot branded crank after the cotted axles and Nervar cranks were removed.





My Phillips Twenty was more work as it had an English threaded bb (26tpi) that needed to be re-tapped to 24 tpi before I could install a cartridge bb and a Stronglight model 90 crank.