Time to start over and punt on my block?

Measure down into the bolt hole how far the stud would go. If these’s room mix up some JBWeld and carefully stuff some in the hole leading to the water jacket with a screwdriver. You can also fill in the bolt hole up to where the stud will end up. Let it sit overnight and then if needed use a thread chaser to clean up anything in the top treads. Install the stud with Teflon sealer and get busy building your power plant so you can go have fun.