L76 to LS3 conversion

[PatmanSeven]

I have a 2009 G8 GT (L76 6.0) that I have DOD deleted and installed a stock LS3 cam. Essentially this gives me a 6.0 liter LS3, with 3.3% less displacement than a "real" one. I know that the MAF and injectors are the same between a GXP (LS3) and a GT (L76). The throttle body does show a different number. Is it safe or wise to simply copy the timing and fuel-related tables from a stock GXP file to my GT tune to create a baseline tune for my Frankenstein? I believe this would give me a HUGE head start toward finishing the tune, if doing it this way is possible or advisable. BTW, I do not have access to a dyno, so I see this as a way to get similar-to-stock-LS3 performance with proven stock durability. The LS3 stock is about a 50 HP gain over the stock L76. FYI the ECM is an E38.

Anyone out there actually done this before?

Thanks in advance,
Pat

[Xjas]

Still need to tune it as you would normally, conservative spark until the fuelling is dialled in with a wide band and then see how much spark makes it happy and doesn't knock.
While the LS3 cam is better, the difference between a an L76 and an LS3 is about more than just the 3.3% capacity, the LS3 has a larger bore size which reduces shrouding of the valves giving the engine better air flow characteristics.

[PatmanSeven]

Xjas, I appreciate the guidance. Makes total sense.

Thanks,
Pat