NO, NO , NO , NO - do NOT precoat the cylinder - that will definately skew the numbers. Besides, all that filling and draining is unnecessary!

Do as Andy said.

Pull the rockers so the valves don't open. Flip the motor so the plug hole is up and level. Bring the piston to TDC, fill the cavity using a burrette (measuring in cc's). Record that volume. Bring the piston to BDC. Fill the rest of the bore using the burrette (this will take a LONG time 'cause burrette's hold surprisingly little). Record that volume and do the math. If you screw up, empty that cylinder and then do it again on a different cylinder so that any fluid residue doesn't skew the numbers.