the block is a 1959 i have some of them for core blocks to build 468to 496s and is just a 454 all 454 s say hi per on them as the 454 was a special order in most every thing from GM but not the nova in 73 front pad by head may tell you some things but it is a low hp engine 1975 gm stop making big number engines the block and heads are ok for the base of a hi 400hp + engine