Supposed to be a different cam ring in there, the rest of the parts are the same as the rest of the pumps.
Your IAT's and EGT's with a GMX turbo and no intercooler were probably very high even for anyones performance tune (thinking that may be why you holed a piston and had cracks everywhere).
I'm with you though, I'd like to think the 5068 does more fuel. Dunno. I've got one for parts that I wanted to mix and match parts into a 5288 or so (have tons of those is why...) that it'd work with my '95's programming.
Next time to turn if up consider an intercooler and a HX Holset turbo for more air, some 18:1 pistons would certainly help it live too.
What was your dyno results?
1982 C10 SCSWB 6.5TD, mods too extensive to list. (13.69 1/4 mile @94.6 MPH) RACE TRUCK
1982 C10 SCSWB 6.2NA, 2.73 700
1986 C10 SCLWB 6.2TD 3.73 700
1989 V20 SUB 6.2NA, 3.73 400
1994 G20 VAN 6.5NA, 3.42 60E
1994 K20LD ECSWB 6.5TD, 3.42 80E
1995 K20 SUB 6.5TD, Wrecked, ran into by stupid teen.
1995 C3500HD DRW 6.5TD, 12' Flatbed 5.13 80E
1995 C3500HD DRW 6.5TD, 18' Rollback Wrecker 4.63 80E
1994 C20HD ECLWB 6.5TD 3.73 80E Wifes Truck.
1995 C20LD ECSWB 6.5TD 3.73 80E
1995 K20LD SCLWB 6.5TD 3.73 80E
1996 K30 DRW 6.5TD 4.10 80E
1997 C10 Tahoe 2Door 2WD 5.7L to 6.5 Conversion Underway