14mm head studs? Hello 30 psi!

In my limited metallurgical knowledge, I think GM's problem with the Northstar 11x1.5 threads was stress corrosion cracking.
Not sure if the 14x1.5 thread is enough larger in diameter to reduce the stress enough not to have that problem or if the difference in casting alloy would eliminate it.

Do you know what alloy Ferrari uses?

I have needed odd quantities of ARP studs for unconventional projects and I just call them and tell them what I want and the send it. I had custom studs made years ago, like 1999. The company is top notch, expensive, but top notch. It is much easier now that the tuner crowd has been blowing up stuff and needed more metric stuff. When I started getting custom studs, they would put standard threads on the nut end because they didn't make metric nuts.
Anyway, just call them, they will work with you.

14 in the block, M11-1 I think it is for the part that goes through the head. The ferrari studs are long and basically pull from the main bearing area not the deck so they need the larger OD to be stiff enough I guess. The only problem I've seen is the head gasket leaks a bit around the studs and the water cause the studs to corrode the aluminum head and block. The threads in the block are deep so they seem fine but the body of the stud become stuck in both the block and head, making removing the head a bugger you need to make a puller to get the head off and trying to remove the studs from the block can destroy the threads. On the 308 and TR heads I opened up the holes a bit to make the binding near impossible and also use a bit of sealant around the suds.

I coould never find out what the block alloy is exactly..."proprietary alloy" is all I found.

....but 30psi is known OK(ish) on ferrari engines

I finally got OnShape customer support to find me a workaround for a bug I found (that they won't admit is a bug) and was able to model this up.
Because the pin block is very hard, milling this won't work, it'll have to be EDM'd.

So the prototype machinist recommended I have this EDM'd because it's hardened.

The machine shop sup at work said he had a cutter that could do it, but he'd just need some time when the boss isn't around, etc.
7 months later it was still on his desk.
So I snagged it and took it to the EDM place.
Two weeks later, tada.
Ooooooh, shiny!
The surface finish in the cut is REALLY good... but that's what EDM does. Per my model, the minimum distance from the notch to the pin bores is only 0.025 or so... pretty good fixturing to cut that without screwing it up.

I had 275 4 cam block with a head stud broken flush with the surface. I ended up taking it to a tool and die shop and they used an EDM machine and "burned the stud into a thin wall tube and at the very bottom "burned" it into a set screw and an allen wrench took the stud right out. Never touched the block and the threads were not damaged at all. It wasn't cheap but given the block was unobtainium, it was worth it.

On each bank of a V engine, there's are two rows of head bolts... one "inboard" row close to the V and one "outboard" row in the "outer wall" of the block. I'm also thinking that in order for a wire EDM to be able to cut the stud like that, the bottom of the stud would have to be accessible... IOW the tapped hole in the block is not blind.

I don't know the right term right off, but I know there is a different type of EDM that can cut arbitrary shapes, but needs case-by-case tooling production... That's all I know about that, beyond it being expensive.