Actually i185 was developed maybe even earlier than La5 (LaGG with m82 engine).
more info here:
http://www.airwar.ru/enc/fww2/i185.html (if you can read Russian or willing to put up with Google translation)
As to the sim aircraft modelling - I would think the model should at least have the same or close basic performance figures (such as top speeds curve and turn times) to the real thing?
Currently some of the FMs are too optimistic, we are giving these figures here to let the devs know this is the case and needs to be addressed in order to make the game more realistic. I'm not submitting C++ code to patch their existing sources
