Just dug out my copy of Squadron's F2A Buffalo in Action and found out the following:
Four squadrons of Buffalos were assigned to Singapore, Nos.21 and 453 Squadrons (RAAF), No. 488 Squadron (RNZAF) and No. 243 Squadron (RAF). It also lists the colors as follows: Uppers - Dark Earth and Dark Green, w/regulation Sky fuselage band and Medium Sea Grey squadron codes. Undersides were two colors, Port (lower left) was black and Starboard (lower right) were Sky with the dividing line being down the center of the lower fuselage. Squadron codes listed: 453 - TD, 488 - NF and 21 - GA. None shown for 243.
You should be able to match these colors with Model Master, Humbrol or Tamiya.
I think I learned not to trust the instructions colors back in the days when we were told that all German aircraft were painted Dark Green (or OD), Light Green and Light Blue and all British aircraft were Dark Green (or OD), Brown and Light Blue. Granted, todays instructions are much better in this respect but you still need to check to see that they are correct. And the decals can be just as bad (I've got three sets of 1/72 decals down on my bench for the same aircraft, an F6F Hellcat. One out of the kit and two different AM sets. None of them match!) No need to give up on a kit because you can't match the paint the kit instructions call for - the biggest percentage of the time (especially on old kits) they're wrong. Hope this helps a little.