In fact those are plated studs, that are not that cheap to buy. So if those studs will work with the new manifolds, I'd just use then and if you really want to have all 6 fasteners on both sides, just use two of the bolts that came with your new manifolds. You may have to run a thread chaser in the holes in the block for the bolts since due to the age of the engine those threads are probably corroded. I'd spray them with something like Kano Kroil and let it sit for day. and try to use the thread chaser (match it up to the bolts) gently. I think the 4 studs would work fine though, I never had any trouble with the bat wings not sealing over the years. I actually prefer the studs greatly because they do not corrode, the nuts come off very easily and the manifolds will side right off. I think its a better way to attach them except in an installation where there is limited space.
