What's the difference between a regular 292 and the industrial/heavy duty 292?

I'm fixing up a '59 f250 and recently got a '59 f500/f600(not sure) for parts. I always though the industrial version just had lower compression and was slower. Recently someone told me the only difference was it has stronger, larger valves and should make more power.
I already had a standard 292 in good shape that I planned on using.

 

There mas a Medium duty 292 and a Heavy duty 292. In 1959, the HD came with a 4 barrel holley, and a special distributor that was setup for governor. The valves were larger, but only in stem diameter as it probably used sodium filled valves. Internally, they used the same crank and rods as the MD engines.

1961-1964 the heavy dutys had forged crank and heavy duty rods.