w124 17" split rim wheel question

^these are 18" but cost about 4k pounds
Does anyone know the correct offsets to get in 8"fronts 9" rears the most "dish" and also the right tyre sizes to go for to give a little "stretch" but good comfort
i'm going to get the inner arches rolled a bit to give a little more clearance.

.this is what it looks like at the moment-i want to colour code the rim outers




