I agree with xderelict about the weld.
Try different gaskets. Replace the end pins with studs if it still has them. Use the cheapest gasket you can find and don't over-tighten.
I originally tried a three-piece Felpro that cost $30. It lasted a week and a half. In the last 15 years I've had two cheapo $6 gaskets on it, replacing the first, five years ago with the engine rebuild. This last one leaked a little at first because I over-tightened it. I think mine are Heddman
