There is Walt Pyron's P-39 for 35's in the July 1959 issue of American Modeller, a beautfully proportioned stunter, very scale like.

There is William Simons P-39 stunter, 56 inch span for 35's , not so scale in Flying Models (1968, can't remember the date, sorry)

and there is Robin Woodhead's Bell airacobra stunter, 60 inch span, 35 to 40 engines (nice) from Aeromodeller August 1973.

The only P-63 I can think of at the moment is Allen Brickhaus's profile stunter for Fox 40 or thereabouts, it's a model of the clipped wing racer "Flying Red Horse" from a MAN issue of 1978, once again I am looking at scanned pages and the actual date is not visible.

I think the nicest is Walt Pyron's.