576 SMALL BLOCK HEADS

They now measure port volume on teardown. They assigned the wrong port volume to the 587 head. They gave the 587 head the same as most others,but they didn't realize the 587 was produced many years after the others and it was produced as a performance head and was bigger. This made the 587 where it can't be used for stock any more.
The 915 can't be used after 1972.
Many use the 587 for 1973 and newer.
I have 2 sets of completed 587.here and another set at my warehouse near San Antonio. Unfortunately I have one of each set here. I plan to go to San Antonio in the near future. I have many casting o different numbers out there.