About the engine oil analysis don't forget about cam bearings possibly being worn, if you do take the engine in for a hot tank treatment they will remove those anyway because otherwise they would be eaten out by the caustic hot tank solution.

On the stainless studs... There are a couple of grades of stainless bolts, 18-8 and 316 being a couple, of those, the 316 are stronger. There may be other grades in there too, as I know there are other grades of stainless plate steel.
As many studs as there are to carry the weight of the manifold stack, I think they will be plenty strong, just don't forget the anti seize. I mean torque spec is only like 10 ft/lb to hold the manifolds on to the head, certainly not enough to strip them.
And on torque specs, when you get that low in the ft/lb scale, I'd convert it to in/lb and use an in/lb torque wrench. I certainly wouldn't convert the other way for those fasteners that need that treatment.
I have several torque wrenches and I don't think any even go that low on the ft/lb scale. On a needle type probably barely enough to get any deflection of the needle at that point.

Honestly for those that have been at this a while, I'd say those bolts Don't get actually "torqued" very often, usually just tightened by "feel" especially when done in the car. By rights they should be torqued for even clamping force being as long as a manifold stack is.....

And you should be able to take the pan, the pickup screen, the rockers with the shaft, the valve cover and timing cover in to the machine shop so they can stick them in the hot tank as well.