How did you fix your valve cover leak?

Cruiser,
Put a 6" nail in the garage wall. Write 'antique' above it. Hang all cork gaskets on the nail.

Edelbrock make a thick rubber gasket which is a 'sandwich': two pieces of rubber with a steel insert in the middle. Not sure if they have for the slant.

If not, one thing you can do is 'make' a silicon, which I have done a few times.
Remove old gasket & clean surface back to bare metal. Fill the gasket trough with silicon, up the level of the lip on the v/cover; leave for a week to fully cure. There is your new, forever, gasket.