So you are basically saying the L model is a better representation of the later J model than the J model we have in AH?
I'll kick it around a bit.
There is a pretty good argument that the L in AH is really a J-25-LO. The P38J-25-LO had dive flaps and boosted ailerons as well as all of the previous mods (larger internal fuel tanks due to conversion of the leading edge from engine cooling to fuel storage, chin radiators and some other stuff not modeled in AH)
The major engine difference in the L versus the J is the altitude at which the engine produces its normal rated power. The J produced 1100 HP to 27,000 feet. The L maintained 1100 to 30,000. In AH this isn't modeled. If you compare the performance charts in AH they are identical when the L should have a performance boost over the J above 27,000 feet. So the L model in AH is actually a P38J-25-LO when it comes to performance. The L model had a bunch of other differences that AH doesn't model like power plant control automation features.