As much as I love all things 'Phil',I really couldn't justify the expense of a Phil Wood bottom bracket for this project.A good,budget alternative is to source a NOS Shimano UN72 cartridge bottom bracket on eBay and lock it into place with a pair of Phil rings. It can only be a UN72, which can be had for around $30, as this is the only one that works with the aforementioned rings.
The UN72 comes with a pre mounted,ISO British thread,locking ring.You need to cut this off.
Hold the cartridge with one hand,and gently cut away with a hack saw.Do not attempt to hold it with a vice or clamp!
The pre installed locking ring is made of a fairly soft alloy.You will know when you are through as the cartridge shell is made of hard stainless steel.Gently prize the old shell away with a screw driver.It should pop off quite easily.
Hey ho,set to go.I should mention here that you will need a Phil wrench to lock the bottom bracket into place.In fact you will need two.French bikes had righty tighty threads on both sides of the bottom bracket shell.When you tighten one side,the other side will tend to unscrew,hence you need to hold it in place with your second phil wrench. Rather than purchase the more expensive 'proffessional'wrench,I suggest the cheaper 'consumer' tool,which you use with a 22mm spanner.(at the bottom of the picture)