The Marans you've got sound a good type mate

cockerels can make 3.5kg but it takes a while.
I love there dark eggs and bred them and Welsummers about 10 years ago.
The Marans Hens i have now are off a mate I gave eggs to years ago and got some back off him after the fox took all mine.
Most just breed for egg colour and forget the DP utility qualities of the Marans, they used to be quick maturing but I think that was along time ago.
I'm going to make a start next year keeping an eye on egg colour but mainly looking for big, quick maturing birds, hopefully a few generations and I might see a difference.
Do you know the sex of yours yet mate? If the cockerel used on yours was bred for a lighter colour the male chicks will have a larger white spot on there heads.
I suppose in our case it doesn't matter as we will raise them anyway for the table.
PS, I thought you had 18 Sasso chicks?