Richard if you can’t find a used set then Fransens have some ‘new’ ones at 84 euro each https://www.citroen-traction-avant.com/en/shop/article/DS%20121-010/Connecting_rod_without_half_bearings_new_compatible_for_11_perfo
CAS are 92.07 for the same con rods
TOC Club Spares are listed at £62.83so you will have to ‘shop around’
You need the crank ground 1st to see what shells your going to need and that will determine the overall cost.
Good luck.
David Faulkner