05AB1E, 37 34 bytes
93ÝãDžy+∞x64&+₃+Ƶ₁L64K30+â)33+Iè`‡
First input is [source encoding, destination encoding], with 0 representing JIS, 1 for EUC, and 2 for ShiftJIS.
Second input it [byte pair].
05AB1E,
Grimmy
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