I did that type repair back in the late 70`s , it is best if drilling the next hole 1/2 in the previous hole/bolt , overlapping them, break each bolt off by overtightening , using 1/2 long grade 5 , 1/4-20 bolts. CENTER PUNCH TO DRILL , LOCTITE ALL THREADS BEFORE SCREWING IN TO BREAK OFF. Peen the broken bolt surfaces when done . No need to grind smooth , better to leave it peened , will look about like a weld bead when done this way . I did my hemi block that way , in my driveway back then , its still running today !
This is the way humongous pipeline engines are repaired by professionals , when cracked .
