[jan72]

A 1,7 cylinder should have both case and head register diameters of 100 mm. The stock bore should be 90mm.

Both 1,8 and 2,0 cylinders have a 105 mm head register. Case is the same as 1,7. What you have there are "slip-in" 96 mm cylinders. These require the heads to be opened for the 105mm register or the use of 1,8/2,0 heads. This should be the diameter in your heads now.

So, in order to be able to use these heads, you'll have to use 1,8 cylinders and pistons (93 mm bore) or a 96mm set (similar to what you have now). Or use the 1,7 heads you have stored with 1,7 cylinders/pistons. The case is fine.