I ran across the page from the ARP catalog with the torque specs. I think you will find it helpful. I am not sure why their guy was so difficult to get an answer out of. I can't attach to a PM so send me an email at firstname.lastname@example.org and I will email the page to you.
If you haven't assembled yet I would recommend using a three step tightening sequence for the final tightening. For the first two tightenings I would go to 1/3 then 2/3 of the specified maximum torque loosen the fasteners and then retighten to specified torque. After the third tightening I would let the assembly sit over night and then check the torque one last time.
Be sure that the block threads for the head and main studs, the studs (and nuts) are well oiled. I usually pour oil down the holes and then slowly screw the head studs in until they bottom. Go gently as you get to bottom because the oil can get trapped down there and make it feel like the stud has bottomed when it still has a way to go. If you put an allen wrench in the hex hole ARP puts at the top of the ARP 2000 material studs it makes the job a little easier.
If you want to be sure you have bottomed the studs make a gauge before you oil the first hole by screwing a stud to bottom and then cut a piece of welding rod or cardboard or whatever is handy to match the length of stud protruding above the head or main surface. Use this as a go/no-go gauge for all the other studs. Don't forget to remove that first stud and also oil it and its hole.