The variation in compression is a definite red flag, I agree with Rusty Rat Rod that more diagnostic work is needed, first instinct is stuck or possibly bent or burned valve, or seat. Noise from that cylinder is a solid clue, even a bad lifter or incorrectly adjusted valve, any of these could cause low compression. Also strong possibility that the heads have been milled and the intake swap has created a coolant or vacuum leak. Keep us posted on your progress/findings.
