72 340 short block

L2316F at least used to be the TRW number for the 68-71 Hi compression forged replacement piston. Depending on actual deck height, actual combustion chamber cc's, depth of the valve notches if deepened over stock, and thickness of the head gaskets used, exact stroke of the crank, and rod length, all affect the compression ratio.
You could have anywhere form the mid 9 range all the way up to almost
13-1.
Better get some help measuring to be sure what you have.
A 340 for $50 is still a good deal. Congrats.
Alan627b