Not sure exactly what you mean by ‘historically accurate’.
For instance, Germany built rockets because Germany wanted rockets. Britain researched Radar becuase the UK recognized the advantage in it. Goering is famous for eschewing Radar early in the war, thinking it not that important.
So, if by ‘historically accurate’ you mean: recreating the way history played out as closely as possible, then I don’t really see the advantage in your system. However, if you mean: recreate the circumstances so as to allow any power to research any technology, but some having a leg up on others because of certain advantages (like excellent german rocket scientists) then we might have something.
As for the exact figures - game balance is always a bigger consideration than historical accuracy, and i have no idea what the figures should be.