Cast steel porosity and density

I'm repurposing some large 10,000lb cast steel weights for a project. They were in a deadweight transducer calibration frame, so I know they were 10,000lb (at the original location's gravity). They're very old, 1960's ish. Considering the parts' dimensions, I'm getting 0.26 lbf/in^3 (7.19 g/cm3). The porosity of this weight would be 8%. Is that something you would expect, or am I missing something? I have a little aluminum casting knowledge, but none with steel. Modern aluminum casting for industry uses lots of technology to keep porosity to ~1%. I realize the material and the times have changed, so it may be perfectly normal. Just trying to sanity check myself before continuing. Any casting engineers in here care to shed some light?