My tow vehicle is a '98 GMC 1500, which currently has an L30 305 suffering from a worsening case of rod knock. I've been nursing it along for about 5 years, but the end is nearing quicker now that one of my daughters now has a driver license and is driving it to school. I purchased an L31 350 to replace it, knowing that I will have to have the computer re-flashed to take advantage of the additional cubic inches. All of the machine work has been done, bored .030 over, new pistons/rings, polished crank, new bearings, etc. My question concerns the quench/squish dimension. Factory dimension was 0.053 (0.025 deck height, 0.028 thick gasket), but the slightly shorter re-builder pistons and thicker head gasket in the set combine for a total of .075. Bringing that dimension down to approx. 0.040 +/- is supposed to help the engine resist detonation and increase efficiency. In order for me to reach that dimension I would have to have the decks on the block cut down considerably, and use a 0.015 thick shim gasket with my current pistons, or I can replace the pistons with a "taller" (OEM height +0.001"), shave the decks little, and use the OEM size 0.028 thick gasket. My problem is that I am getting conflicting information and advice about this. A friend, who is a trusted mechanic, told me not to worry about it, that it was not worth the effort on a "stock" engine. One of the machinists who did the machine work on the engine told me the same thing. Another friend, who has built some fairly stout racing engines, as well as several others on another automotive forum have told me that it was absolutely worth the effort, even on a "stock" engine. I am also going to change the cam to another GM factory grind that will give me a little more torque, which is why I am saying "stock" engine. Anyone here get "in the weeds" on engine builds?