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We have an LS376/480 Chevy with the G4+ Xtreme. As we are burning 100LL fuel (Leaded), we do not have O2 sensors.

What is your advice for programming under these circumstances? We will be running this engine from sea level all the way up to over 14,000 feet (Pikes Peak).


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Knock ears and lots of plug reading I guess? o2 sensors for AFR monitoring is a fundamental for building a correct tune. 
Or like the old school drag guys would do, keep jetting up until the MPH starts to decrease. Same goes for timing but the use of home built knock head phones would be a great tool. 

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In terms of a fuel control strategy, set load equation source to MAP and use MGP as the axis of the fuel table will be the best choice.  You may also need a 4D table spanned with BAP depending how much the lower pressure on the exhaust side of the engine affects the efficiency.  I would still run lambda probes if it were me - as a bare minimum at least on test days for logging until I was happy with the fuel mixture control over a range of altitudes.  

100LL is not too bad with a max pb content of around 0.56, so you should still see ~500hrs life on a lambda probe.

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