If you do crack the bleeder to compress the piston into its bore, then be sure to bleed that line when you're done.
I usually use the old/outgoing pad to compress piston(s)...that way you avoid potentially marring the face of the piston.
"If everything seems under control, you're simply not going fast enough" --Mario Andretti
1995 E500 street car
1986 Porsche 944 Turbo S track car