How much experience do you have?
http://www.hobbybarn.com has Marutaka kits, which are the best, but you have to know how to fly and fly well. Precise scale.
Indy R/C is a good place to look for custom gear. If, you can find any MK kits (Masahiro Kato) they are made with the first choice of balsa from South America (exclusive trade option). I only know of two WWII kits, and neither was a P-38.
If, you're made of money and have experiece with building, then Byron Originals. Take a vacation to the Byron Kingdom this summer. WOW! The Pearl Harbor reenactment is worth packing the camcorder for.
Sig has a Mustang, but it's a plastic fuselage and foam wing. It's a great flier, though.
Top Flite kits are probably the easiest to get into, both from a cost perspective, and from flying aspects.
Unless Bud Nosen kits have improved, they have nice giant scale plans, but the wood sucks.
Frank Tiano used to have some pretty good offerings. You might know his nephew? Tom Cruise?
Larry Jolly has many custom aircraft bare-bones kits. L.J. does all the R/C work for Hollywood. That was his Zero that exploded in "Final Countdown" and he did work for "Baa Baa Blacksheep," as well as the airliner for the movie reenactment of the flight that lost the top section on the way to Hawaii (forgot the flight number). Nearly everything he has done is available in a bare-bone. Airwolf too, but I doubt you want a Heli.
Stay away from Greg Namey's kits, plans, and anything else he has to offer.
ARF's? I don't ARF.
Good luck, have fun, and when you're ready to dogfight, let me know.
