Looper head bolt size

Hello!
Can anyone give me the correct head bolt size used on an -87 V6 Looper?
I need some specs because I am trying to order some head studs from a specialised bolt company here in Sweden.
I have found some good looking stop screws, but someone told me not to use them because they are made to push and not to pull...
//Anders

5/16-18 UNC for the end that goes into the block. Normal class 2A thread tolerance. I would insist on a minimum of 7/8" of threads.

Thanks Barry! Just the kind of anser i was looking for:D