From the numbers on the engine block and head, it appears as though I have a 54 engine block with a 56 head......Now, i was told the engine was overhauled, it looks as though that is correct, but I cannot turn the engine over even with all the help of additives and a crow bar.....i was wondering if there is something wrong with the block/head assembly that may have the pistons blocked??????.....Anyone got any comments or ideas??