Well, all the R-10's as originally delivered had its initial interior paint scheme with blue doors and grey walls, and so did R-7A #1575 (the prototype) after its *rebirth* as the R-10 prototype. As a matter of fact, #1575 is still sporting that same interior scheme as intended after my visit to the Transit Museum just last weekend.
The official Board of Transportation photographs that are in my private archival collection do separately show #1575 and a typical R-10 car as new with those blue-and-grey interiors. However, I remember a certain number of R-10's in the 1960's to have a repainted solid "Patterson Green" interior, and this is evidenced in looking at James Greller's book "New York City Subway Cars" with a picture of #1848 (later known as #2995) as proof.
For those batch of R-10 cars that were painted in that firehouse tartar red exterior setup (like the R-29's) in 1962, the interior for them was purplish blue for the doors, bright orange for the walls and solid white for the ceiling. Ironically, this same particular interior scheme showed up also in R-9 car #1741, and this experimental color usage were set to be based upon the official flag for the City of New York.
-William A. Padron
["Wave Crest"]