If you look at a front view of the full-size Ki-61 you will note that the wing has dihedral and the gear leg is straight down. The 85 deg unit will most likely be best for achieving this configuration with your model. I had the Don Smith Ki-61 with 90 deg retracts. In order to keep them within the wing cross section while retracted they had to be splayed outward when extended. I got a deduct at every contest I entered. I had the Royal Ki-61many,many years ago.
Chuck