So I recently tore down my 390 in my 63 galaxie. Car felt underwhelming power wise and only had about 15psi of oil pressure hot when idling. So from what I can tell I have a 360 crank in it with long rods, and a 390 piston. I’ve had some trouble finding info on whether or not the 360 piston and 390 piston are the same. My question is with this combination do I have 360 ci or 390 ci of displacement? And why would someone use this combination of parts? I’m gonna build a striker out of a different block, so really I’m just curious now about what and why I have what I have.