I'm working on the same plane but I made a few changes. After some exhaustive research, I've added some things to the antennas that I found were particular to the P-61B's. One was the red wings on those H type antennas. The other is the cat wiskers up near the front of the plane. I also noticed that there is an egg on a stick shaped antenna that was located in different places depending on the unit. Finally, I found that there is an often over looked scoop on the starboard side near the back seat. I know not all the P-61B's had this but if I can, I will include it. The window hatch for the back seat also has a red handle that sticks out. I've been successful in makeing this. The fender on the front wheel had two supports attached to it. I'm trying to fabricate this as well. I hope my model could look as good as yours. I'll post some pictures when I can.