Not true! Those replacement blocks still have the extra head bolt bosses in the valley for 6 head bolt heads like W8-W9 and Indy's as well.
I helped design those lifters Comp now sells, and they will clear everthing in the block EXCEPT for the head bolt boss!!
You will have to cut or grind that boss...you can trim it down with a porting tool or just knock the majority of it out but be carefull as water sits just .200 behind the valley wall.
Once you do this, your smooth sailing. I can sell you those lifters far cheaper than Comp can when your ready...as well as a nice cam for your intended purpose.
Brian
