DC, the head was mill .250, 1/4". Don Wheeler out of the Denver area told us what we could do with the 320 Buick. Yes, the pistons were domed, they came from Venolia, don't remember the compression ratio, but was pretty high. When we went to the 4-71 blower we changed heads and didn't mill it to lower the CR. That worked great until last summer on the first run we suffered a burnt piston and our fun was over for the year. We are in the process of rebuilding and changing over to efi.
