Bummer man! I always hate SOA for not acknowledging that the HG's suck as a result of their engineering or Q/A oversight and offer to help a owner out when this problem arises even after SOA announced they resolved "all HG issues from previous generations"
Two ways about it, pull the engine do the HGs on the bench or leave it in the car and remove the heads.
People argue for both methods and i get why you would pull the engine but I wouldn't pull the engine unless you can verify the matting surface on the block is warped. If both surfaces are true, removed the heads, clean things up and use a quality replacement HG.
Very nice one part video:
2.5i Head Removal