SOLVED BY MARK ALBERTS:
The piston appears to be from a Merlin engine on a P-51... but not just any P-51, it could be from what would become the world's fastest piston aircraft - the "Voodoo", which was owned by Bob Button (that appears to be one of the signatures on the piston - B for Bob, then a drawing of a button over the name of his plane - the Voodoo).
 
Adding weight to that is another signature on the piston... Curt Brown, Pilot of the FB 11 Sea Fury "Sawbones" who placed in the top 10 at the Reno Air Races in 2013, 2014, 2015, 2016 & 2017 (and Voodoo, owned by Bob Button but flown by Stevo Hinton, was there during all of those years - winning first place on a few of them).
 
There was a Joel Swagger in the top 10 at a few of the Reno Air Races during those years...the J? signature could also be Jose Flores who worked on the engine for Voodoo.