leaded or unleaded fuel

I have said this before but the ironic thing is that a 10.5 340 piston was based off a 62 cc head(shaved) and a .020" piston above deck height(block decked)
How Ever! the 11.5 domed pistons were 11.2 with out shaving the head and with out decking the block.
When i build my first 340 and figured out it was only going to be 9.4 i bought one, 11.5 piston, hoping that it would come in around 10.5 NOPE 11.2 So i settled for the flat top at 9.4:1
If i new then what i know now, i would have ran the 11.5 piston, on 91 octane fuel and been happy!