It can be easily done. And codes wont be an issue since you won't need the ECM. I let the ECM run the fuel pump cycle, but oil sender controls the fuel pump when it sees oil pressure.
It's all bolt in. Just be sure to get the correct Vortec flywheel for your externally balanced crank. I used Holly intake, Q'jet with mild jet changes.
Don't know where you are located, but the truck will not pass inspection. Might not be a problem. But, technically speaking, it's "off road" toy.
And your NV4500 will easily handle a basically stock. A Cummins makes 6 cylinder torque st 450-1000+ lbs between 1200 and 3000 RPM. A Cummins will destroy gas engine NV4500s. Even now Cummins severely detunes their manual shift diesel output trucks. Your Vortec will make smooth power up to maybe 450 lbs at 4500 RPM. Huge difference. Unless you go in for major off road....or your transmission is already crap, it will be good behind a gas engine.
Really. The only complicated (relatively) item will relate to creating circuit that protects you air conditioning compressor when operated as stand alone.
The ECM will not allow the AC when it cannot see a run signal. But the AC can be made functional. Cruise will work without ECM as long as the speedo works.
The fuel pump will require changing, or use regulators. I used factory GM FI fuel pump with two regulators. One to get down to about 10 lbs, and the second down to 3.5 lbs. Worked without issues for 5 years.
My conversion was in front of an NV3500.
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