If the pins still hold tight then I'd use silicone RTV. It will give you a better seal and no worries about it "welding" the pins into the cast.

It drills okay, more like a "plastic", which of course it is. Use a high-speed, SHARP drill bit at high rpms to get the cleanest job. Use a drill guide to get the hole true. It's very easy to go off-center through the epoxy.