At almost 300k miles my 97 850 glt cracked a sleeve. I have a 94 850 with a good motor. So im planning in using the long block in my glt and keeping all the factory LPT turbo parts. The NA engine having 1.5:1 more compression i would think the factory ecu wouldn't be able to compensate even with high octane. My thought is i could have it tuned to run safely. Has anyone done it and who would be the tuner of choice? Now i have a machine shop that can repair it but by the time its all said and done ill be $600 in the hole and a whole lot of down time.