Welcome.
Everything I say is meant with humility and politeness. Take no offense, it will be hard to answer such an open question without knowing perimeters. You noticed they quickly fell to argument above.
You are given the simple and correct answer by AK DieselDriver above- luck. Yes, I agree. That is what made the difference many days at the racetrack for me.
More directly: You need knowledge.
Running a stock compression 6.5 at 30psi - I’ve done it several times both single large and smaller twin turbos.
You need to understand that you were building a dragster engine by doing that, not an engine is built for lasting 20,000 miles. You need to understand that it is not a question of IF you’ll blow a head gasket, warping head, twisting the block: you WILL do damage it’s just a question of how well you build the engine as to WHEN it happens in 1000 miles or in 18,000 miles. Do not be confused, you will not get over 50,000 miles doing it, regardless of money spent. I lived decades trying high compression with high boost. My current build has a set of 18:1 pistons going in for a reason. That concept of high compression plus high boost is simply not the best.
Moving forward assuming that you are trying to build a toy not a Street driven pick up to get to work with:
True deck the block after the block filler (at 60% jacket capacity) has cured 60 days. Ignore the difference of spec ring gaps for cylinders 7&8 and gap them the same as the other 6. Reversed coolant flow going in all 4 ports and out the pump ports using positive pressure pump, not an impeller pump. Head studs, oring the block and copper head gaskets.
Note equalizing the ring gap - unequal pressure will warp the head in minutes under that cylinder pressure. So having the rest of the system balanced should go without saying, but for the benefit of readers that don’t know how to build a race engine- the rotating assembly has to be balanced, the injector pump output has to be balanced, and injectors have to be balanced. Without this imagine an engine running 25% less power in 1 cylinder- as the block and head flex if one is not moving as much as the others, it will open the gap and blow the head gasket in minutes. I had it happen before the truck made it half way down the 1320 before. As to the bottom end of the engine- full girdle, scat crank.
I suggest a short study of blown alcohol dragster engine concept. Because the cylinder pressures you will create with that high compression you will create is in that category.
Starting with better flowing heads to help fight the heat complications would help too.
Top cooling system is a given must.
If you are intending on using this as a towing or daily driven truck on the street and not doing $10,000 worth of build, just throw studs in with felpro +.10 gaskets, ignore the how to stop head stud leak write ups done and just gob on ultra grey to the threads. Have junkyard engine #2 done at same time so next month or so when this one goes, you can just swap engines because it is faster than doing both heads in the rig. And you have the truck running the same day each time. Still balance the pistons/rod assemblies but dont bother with crank and machine costs. Just use a scale and home tools. The failure rate will make machining costs not worth it as you go through engine parts. This way doing it with my friends when we were young was some of the funnest times we had wrenching- so if this is the route- enjoy it! I miss those days.
