Not saying this is going to happen, but I put a 383 together with the Mopar performance steel shim gaskets, “ heads and block were NOT surfaced” used copper spray, re torqued after break in, and still had some water seepage, into cylinders and side of block.a good fresh deck and head surface would be best and recommended, but I pulled them off and replaced with felpro 1009s, no issues ever since. And just so you know, I measured the Mopar gaskets at .018 compressed