My builder has not gotten back with me yet but I’m pretty sure it’s a stock bore so he will go 30 over. As for the pistons I don’t know. I’m using felpro head gaskets and bolts for the head. If there is something wrong with that I would like to know now. As far as heads they are the stock aluminum and my builder called comp cam as order the beehive springs and hardware to fit the lt4 hot cam.