i don't know about any official modifications with 2 UB instead 2 schkas/2 shvak in wings + 1-2 shkas, was only some various experimental works with TKB-150 (name of UB in 40) and 12.7 mm variant of shvak too, and how said Luno13 in mass serial production with 1 UBS + 2 shkas was only type 29, but, we can't really say what not was some not mass field changes (i not saw any info about this), plus, was armed UTI-4 with 2 UB (type 15b) -
in total, now we have type 18/"24", so, without serious changes you and we all can get correct i-16 type 24 (m-63 + 4 shkas, now in game type 28 in fact, if i'm not wrong), type 28 (m-63 + 2 shkas/2 shvak) and not so powerful heavy armed type 27 (m-62 + 2 shkas/2 shvak), it's all historically correct, balanced (type 24, good engine but only shkas, or type 27, not so good engine but shvaks, etc) and i think more than enough at first time...
be good if DT do late type 29 (m-63 + 2 shkas/1 ubs, 650 planes in total, good performance and balanced weapons)...
type 15b, type 17 + new less powerful shells for shvak (similar with 12.7 mm effect), planes of other countries (chinese, finnish, spanish etc), other early types (maybe, and little experimental series, with different weapon) and little changes for all (like 2-4 rs-82), need too, especially, because in USSR i-16 was used in combats very long time including early types (uti-4 was used how training plane until 1946)...
and interesting fact, in last Maslov's book about i-16 i read what 23 feb 1944 pilot Кудымов had a fight with fw-190 and down him...
how much it's true, i don't know, anyway it's interesting info,
here this fight in his memoirs...