Shop work truck has 290K on it with stock bolts and gaskets. 100 overs, 10mm stroker, and 45+ PSI of boost. On other trucks we have bent and broken rods and put them out the side of the block without blowing LLY gaskets, destroyed pistons, you name it.
The problem is not the gaskets and the problem is not the bolts. The problem isn't X amount of boost or Y amount of horsepower. The problem is simply that the LLY heads are more prone to trapping air. When people run their trucks low on coolant or don't properly bleed the system of air, air will be trapped at the rear of the passenger side head; that air will give the coolant a chance to boil and create steam and pressure, then the high pressure pocket will further prevent coolant from flowing there (liquids flow to area of lowest pressure), the problem compounds until it blows the seal at the rear cylinder. The most common thing is a leaking water pump that isn't taken care of. Guy gets in the truck Monday morning and it says "Low Coolant", but he's late for work already so he says screw it and drives to work saying he'll fill it when he comes out at the end of shift. He gets off work and forgets to bring out a jug of water, get's in see "low coolant" and says "I just worked 8 hours there, I'm not going back in, I'll fill it when I get home". He gets home and lets the dog out, kisses the wife/kids, cracks a beer and puts his feet up, etc and forgets all about it. Tuesday the cycle starts again and next thing he knows it's been a week. Or the water pump gets changed (or any other work with coolant drained) and the system isn't properly bled of air. Pulling a vacuum on the system to fill it is the best way, but if you don't have those tools let it bleed until you get no air for at least 15 seconds out of the bleeder on the thermostat. You will have a gallon of coolant on the floor by the time that happens - most people put the bleeder screw in as soon as the first sign of coolant comes out to prevent a mess. Having the front end up higher than the rear will help also.
We see more blown gaskets on stock LLYs than we do modded ones - mostly because the guys modding them are either paying closer attention to and taking better care of their trucks, or our shop is doing it for them. We see blown head gaskets on other models for the same reasons but they are no where near as bad about it.
