[Cuccos19]

I think what you mentioned "streamlined version" that's actually the XP-49, Hyper Engine driven one, which was a quite different aircraft anyway.
http://en.wikipedia.org/wiki/Lockheed_XP-49
http://www.aviastar.org/air/usa/lok_xp-49.php
http://home.att.net/~jbaugher1/p49.html
http://en.wikipedia.org/wiki/Continental_I-1430

The P-38K was actually a G model with new Allison engines and Hamilton Standard "High Activity" paddled propellers. Only built one or two. The Army pigheads didn't want to stop the Lockheed's production lines for 2 or 3 weeks while they make the retooling for the new - K - model. Real shame...
http://www.456fis.org/P-38K.htm
http://home.att.net/~jbaugher1/p38_14.html
http://www.alternatehistory.com/discuss ... stcount=18
http://www.facebook.com/topic.php?uid=7 ... topic=7661
http://www.aero-web.org/specs/lockheed/p-38k.htm

As for the "What-if", we already have a naval Yak-3!!! Ouch! (nice one, but far from reality)