Here's a tip for putting the heads on. They are heavy and hard to aim - and the heat shield tends to grab the gasket edge. A slip sheet works great.
Put the new gasket on the block over the dowels - then make a cardboard slip sheet to lay over the new gasket - put a couple notches at the bottom for the dowels. Now put the front lower head bolt in the head and lift it into place, aiming the front lower corner of the head so the bolt goes thru the dowel. Rotate the head and lower it until both dowels are engaged - then pull out the slipsheet before jiggling the head down on the dowels.
Great tip here!! I actually had to buy 1 new HG because the head slipped when reinstalling it and cut the gasket.
As far as the exhaust manifold to Y pipe bolts go, I knew these would be trouble so I put the car on jackstands and PB blasted them from underneath twice a day for a few days befors I started the job. They came right off!!