The very first thing I'd check is the weep holes on your water pump. When the pump fails, it will coolant will leak out of these holes, top and bottom. It should be fairly easy to spot.
Yes the sprockets are different....get the earlier timing chain set. Camshaft timingDo you mean the sprocket is different? I don't think you can change that timing with a different chain?
Moving this to the Mark Series section. :wave: