I have to disagree grumpy.
For tube headers you would be want use studs in every hole and replace those locator pins on both ends of the head with threaded studs. The pins are threaded and will screw out if you haven't already done so.
The two original studs were in the
third hole from each end. Every hole down the side of the head is threaded 3/8-16. The stud takes a 3/8-24 nut and is 1 7/8" long.
Originally they had both long and short clamping bars for between the IN and EX runners. I found extra short bars and used only those between the tube headers and a Clifford manifold.
I put studs in all eight holes and it makes it a lot easier to hold everything in place for assembly.
In the picture below there are eight studs, but not one nut or bolt holding anything on the head. To duplicate that alignment with only the two original studs so that you can push a bolt through the manifold, through the gasket and into the head without cross threading anything, will leave you wishing you had two men and a boy helping you to hold everything up in place.
The studs are maybe a buck and a half at NAPA. A 2" stud may be too long in that first hole, but you may need it for a PS bracket or just put a couple extra washers on it.
I don't use grade 8 bolts in cast iron. I'd rather a bolt break than strip the threads out.
I believe the studs are often missing because the head rebuilders remove them and do not replace.