273 block, head & piston info needed

Picking up a 273 engine that has a rod knock for parts .. block is stamped 1969 , the heads are stamped 920 and the pistons have 4 cutouts for valve reliefs, adjustable rockers
It appears that is has been rebuilt at one time and items were switched from one engine to another. my question is the pistons with the 4 reliefs in the pistons >> is that the high compression piston?
Thanks !