If you supplied the block and did not request magnuflux and pressure testing, then its not their fault. If you did request magnaflux and pressure testing then its their fault. If they supplied the core its their fault. There is no good way to fix this. I had a guy with a sb chev the other day with the same problem. You basically need to replace the block. When some one brings in a block and says bore and hone this, then its assumed you know your block is OK. This may not be what you want to hear, but is the reality of these situations. Hopefully your shop will sympathize and make it as right as they can what ever the case maybe.