The 'Cosworth 205' was merely selected for there tighter bore tolerances, if you look by the dizzy you will see four number, representing the tolerance for the cylinders, Cosworth asked for only grade 2 and possibly 3 from memory to be delivered to them.

So you should see 2222 for example.

Once rebored this figure is irrelevant.

In addition they will have YB then a number above the water pump on the front on the block.

That aside it's the same block.

Martin