Since you have low compression across the board, it sounds like the head is not seating. Check to make sure the head is not binding on the head studs as I mentioned before. If that is not an issue, pull the head and make sure it is flat along with the block. Are you using an MLS or composite...
The 6-bolt head studs are larger than the 7-bolts. I'm running the same block and head configuration on my car and had the holes enlarged on the head to accomidate the larger head studs. This might be causing the head to not seat... just something else to consider.