Also, in your pic, the one stud/nut combo doesn't look right. The nut is wrong, and I think the stud is too short. I wish I had part numbers for you, but the studs used on newer engines have a torx head on them. That lets you install them easier. Plus, you can hold them in place while you...
I would not replace the studs unless you need to. Ya know, if it ain't broke. Yes, they can be a problem. Oh, wait, they are a problem after 40 years. Just be careful, and as you are doing, soak the crap out of them. Go buy a lottery ticket if you get them off without issue. Ya, replace the...