Friend has a '66 New Yorker with stock 440. Years ago one of the heads cracked (over heated) so he replaced both with a rebuilt set of 452s. After that he believes he lost quite of bit of power (seat of the pants measurement). This is the non-HP 440 from '66. First of all what heads did it come with from the factory? What cc are those heads? How far down in the hole would stock non-HP 440 pistons be in the block? Trying to guesstimate compression.

He believes that the difference between open vs closed chambered heads are the reason for his power loss. What do you think?