Been a long while since I posted here, but nowadays FTE seems to be the more performance minded IDI forum so here goes....long winded post to ensue.

Slowly but surely starting a build on a 6.9. 7.3 currently in the truck runs great, but at this point, I’ve got enough time and money wrapped up in this thing it’ll probably have to serve as my coffin when I keel over, so figured I may as well build me an engine that will last at least as long.

Truck is used to haul toys (camper, quads, toyhauler , etc.) to the family fun stuff so #1 priority is reliability. After that, I don’t see much sense in going through a rebuild unless I’m upgrading some stuff.
So I decided on a 6.9 since they tend to run cooler and have more beef to the cylinder walls.
So far I’ve drug home 3 - 6.9’s and 1 7.3 so lots of parts to choose from.

The combo:

One of the 6.9’s was a pristine, low mile unit, but an 84 so the undesirable block. So I’ll throw most of the guts from the 84 into a 87 std bore block I just picked up. Then use a few of the 7.3 parts, like the rockers, cam gear, IP front cover, and fuel filter setup.

Already have an ATS 088 turbo and a 7.3 intercooler, but there’s a good chance the ATS setup will go away in favor of a BW S300 series.
Head studs
R&D stage 1 cam
R&D injectors and pump - either 90 or 110cc
R&D billet fuel rails

And finally a few questions....

Any advantage to running the 7.3 “088” precups in the 6.9 heads?

And the main question: decompressed or std. compression?

The cam would decrease the dynamic compression ratio. But not the static compression. It all boils down to cylinder pressure, and how much is required to lift a studded 6.9 head. But there’s no way to measure cylinder pressure, so I can only research existing combinations and how the head gaskets seam to be holding up.

Maybe I’ll reword it: what would be considered the “safe” amount of air / fuel on a studded 6.9 without the worry of popping a head gasket?
Example: would a R&D 110 pump and stage 3 turbo be considered a good reliable combo. Decompressed or not.

Just trying to find the happy medium between reliability and moar powa’, with an emphasis on reliability.

I understand there aren’t enough combinations running around to make a definitive answer; I’m just curious what yall’s opinions would be.