Thanks, that link really helped clear up the differences in the rockers. Luckily I happened to have picked up 235 rocker assembly before I got the block that looks like the pre 58 235 ones posted in the link and has the groove inside the rocker arms. I assume this means I also need the lifters without the notches in them? Are there any any changes they made other than the rocker oiling? And does anyone know what the small oil hole next to the lower 1/2 NPT oil hole in the block is for?