[T3] Engine Re-build

[Larry Thrasher]

A couple of questions on rebuilding an engine.
1. Three of the cylinders show around 133 lb compression and one is around 125. Is this significant?
2. Is there something that goes on top of the oil cooler to seal the airflow from escaping there? A sheet of foam or
some other insulation? 
3. Is there any places that specific attention needs to be given to air flow/leakage in the Type 3 engine?
Thanks.