Off the top of my head:
B-17E, F
Numerous Spitfire variants, more than I can mention here
109E-7, F-2, G-6/AS, G-10
P-47M
F6F-3
Fw 190A-2, A-3, A4, A-6, A-9
Bf 110E, F
Ki-84-lb, lc
A6M3
Various Ki-61 variants
P-40N
Yak-9D
Yak-9UT
All of these would be relatively "easy" compared to adding something brand new, but it's slim odds that we'll ever see them, including the Hurri IIb (why didn't they add it at the same time as the IIC?).