Calling all Olds engine gurus

My dad has been having a hell of a time keeping water pump gaskets in his 68 Olds 442 'vert with a mild 455 in it. The problem started last year. Water pump gasket blew out, replaced the gasket it blew in the exact same spot again. Replaced pump with another stocker and with new gasket it blew again, same spot. Ordered an aluminum pump with a new gasket of course and on the first test drive last night it blew out AGAIN. To recap, this car has had 3 different pumps....2 stock pumps and one aftermarket Milodon aluminum pump.

This is where the gasket blows out everytime. And yes block is clean with no visible damage. This is the result after a test drive around the block.

Any ideas here guys? This engine has been in the car and running for about 10 years. Issue only started last year out of no where. My dad is at a loss and doesn't even want to look at the car anymore.

I guess the timing cover was replaced last summer after the 2nd stock pump started leaking. No silicone on this last try and I didn't ask about the other times. He got a new gasket which looks different in that it's wider around the bottom instead of being so narrow like the previous ones. He's going to try this one with silicone and see how it works.