If you take a look through the water pump hole you can see the walls of the cylinders

The cosworth 205 block was just a selected 2 litre pinto injection block and the walls are standard thickeness

If you look through the same hole on an RS500 (small core plug on the sides) block you will notice that the walls of the cylinder thicken as you drop down and this is the same of the 200 block

It was only the RS500 version of the 205 and the 200 block that had the thickening on the cylinder wall - and it is this thickening which allows the cylinder head bolt holes to be drilled right through for long studding

The later transits had the 202 block but this was nothing special