i have a 230 block, date code is 12/10/71. it is at the machine shop now getting sonic checked. was supposed to have been done last week. it is not the cwb. i re-read the 440 source on blocks and saw that all 230 blocks we not cwb. so i called them and they said that although the cwb is highly sought after, there is nothing wrong with using the std 230/630 block for your stroker 512. my 230/630 blocks are not $1k blocks but probably $500.00 blocks after sonic checking and hot tanking.