what piston did a 318 use?

I have a 68 318 engine and it states that it is 9.5 to 1 comp ratio my pistons have valve cut outs in them both sides I know they are factory ones as I have owned it for 32 years and both previous owners were known to me , I also have a 78 block and the pistons are flat top and 30 thou lower in the bore than the 68's hope this helps