Compresions and plugs photos suspect block or head

Below is the pictures of the plugs out my p38 thor which may have a cracked block problem or is it a cylinder head.
Also I did a comprehensive compression tesst on all the cylinders
compesions in psi

8. 165 7. 163
6. 180 5. 178
4. 163 3. 168
2. 175 1. 188










My first imprssion is the trouble is at cylinders 4 and 6 as these are very white clean and the insulator is slightly pink(colour of coolant) more so on 6.
Concern goes to 1 and 3 where its looks very burnt and plug 3 was very difficult to get out. These plugs are only 1000 miles old and are double platinum.
Are there any more water way between the head and the block apart from the large one at the rear of the head/block ?

The compression readings come in around 10% deviation, which appears to be o.k.
There is a marked difference in the plug conditions between cylinders.
I have found from first hand experience that fairly consistent compression figures between pots can still lull people into a false sense of security. Just remember that the process of taking measurements involves cranking the engine on the starter and taking the highest reading..normally this is done with the engine warm or even cold. Whilst it creates a level playing field, it will not pick up a slipped liner or porous block and is more likely to highlight either a blown head gasket or leaking valve.
You have done the heads and are still losing water, my opinion, for what it's worth is that you have block problems. Have a read of the write up on the subject on RPI's website for more info.