Your freeze plug problem is most likely due to who installed them 'Dry'. I used the Permatex red super tacky gasket adhesive, the kind that comes in a small can with a brush (or little sponge) attached to the cap, or the brown 3M glue adhesive that is super duper strong and gasoline impervious. Don't be shy with the sealant on the freeze plug and the block, goop them up good and if your worried about the excess outside the plug, just trim it off when it fully dries. (edit) your freeze plugs could be punched it just a tad further, just so you can see about a 1/16th of a inch of the block bore hole. Look at close up of original pictures of a factory installed block and you can see the plug is just a little further in. I'll see if I have any old pictures of what I mean. .