K4N head gasket on MM55sr

Hi everyone, I have an old excavator and am trying to get her back to better function. My main problem is overheating and I have bubbles in rad so head gasket. I am looking for gasket supplier in BC or Western Canada. I am using a 7 pound rad cap and have tried a 13. Which is proper for K4N? I am interested in your thoughts. Thanks for your replies. All the best from farmerboy.

K4N head gasket on MM55sr