I had that problem once, when I used ARP head studs with Edelbrock heads. On one side of the engine, the head stud (which is a little thicker in diameter than the stock head bolts) was right up against the side of the hole in the head, and completely blocked off the oil transfer slot machined in the deck of the head, keeping oil from getting to that side of the engine. I ended up chamfering the bottom of the head bolt hole so that it extended out a little from the original hole, and then the oil could get around to the other side of the stud, where there was clearance between the stud and the hole in the head, and everything worked fine. You might have a similar situation with your head bolt.
I found this on my engine prior to any damage, because I always pre-oil with the valve covers off, to make sure the valvetrain is getting oil. Always a good idea to do that. As far as the head gasket goes, I wouldn't worry about; I'd torque the bolt/nut to the original specs and I'm sure it will be OK.
Also, the lash adjusters are not supposed to be centered; they go towards the outboard side of the port, to bias the pushrod a little ways away from the port. Gives more clearance for the pushrod in the intake manifold hole. You should have 8 rockers with adjusters biased to the left, and 8 rockers with adjusters biased to the right. One of each for each cylinder. The sets of 8 should be the same; if the adjusters are offset by different amounts, then you really did get a junk set of rockers.
Hope that helps - Jay