Some interesting data I've put together.
I found a video in... arabic? that showed measurements of the block head bolt holes.
Threads start 6mm from the surface.
The hole is actually 46mm deep total.
Time-serts for head bolts appear to be 12L14. This material run 60,000psi tensile strength, but sheer for 12L14 is 11600 ksi = 11600000 psi!
Realoem puts the head bolts at M10x110 for the M54. Those bolts are 4.3 inches long in the threaded portion.
The ARP S52/M52 stud set is only 4.5 inches long with a lower thread that's .95 inches - that's just over 24mm of threaded rod.
However, considering that the ARP nut and washer is pretty tall, I'd bet that when they were used, the studs weren't even threaded all the way into the block.
I called ARP and bugged them a bit about possible studs.
Edit: ARP makes a 5.1 inch long M10 stud AM5.100-1LB, I didn't ask them about sets but they probably come in one.
ARP makes a M11 stud that's 5.35 inches long. It's a bit bastardized as it uses a standard nut up top to reduce cost.
https://www.summitracing.com/parts/arp-atp5350-1lb/overview/
Singles are ARP ATP5.350-1LB at $15 each, but they sell a kit for hondas is ARP 208-5401 that includes 10 studs, washers and nuts for about $115 or so retail.
Add four more and we're still well under $200.
The rub - the threaded portion is about 1 inch long. Only 24.5mm of threads.
ARP also makes a M12 stud that's 5.4 inches long.
The part number for individuals is AU5.400-2LUB.
The 10 pack kit is ARP 204-4706 and it's made for audi/vw diesel. It's also made of ARP2000.
According to raceware the M10 stud set has approximately 30mm (1.18 inches) of thread on the block side and is 127mm (5 inches) long.
According to their web site, the hardware is rated for 205,000 psi tensile strength.