Epilogue (until a complete test)
I tried another filter design, the "donut shaped filter", made of a solid foam:

At first instance, I was disappointed to see that it didn't fit in the bowl either :

But its length was right. So a little of filing and it let itself in, alleluia

:

As the gaskets have the right sizes:

hopefully the set up will work fine, with the fuel flow coming in by the center and going out through inner and outer faces of the foam material.
The filter in the bowl and its bracket:

Quite a relief I must admit. And, with two filters, I have "belt and braces" as we say in french (what is the expression in English?)