Yep, it's been done before. I think TheCommander on RCU did one.
If I do, I'll be cutting it in half lengthwise, and take about 3/4" off one side to make it narrower. Then re-cut the turret ring.. if I have enough room. That way you get the offset turret this tank had.
Other than that, its just a matter of building up some styrene sheets on the hull and turret, swapping the driver & gunners position and some work on the lower hull.. rivets.. bam Jap tank!
Tiger I - Panzer III - Panzer IV - Chi Nu Kai - Panther G - KV-1b 756(r)
M4A3(76) Sherman - T-34/85 - M3 Grant