Here is a picture showing where I made the cuts and what I added for length. I hope this helps. If you are going to keep the Tiger tracks then this conversion is a good one. However if you want to go to the narrow Panther tracks, then you may want to remove material from the overhang. I think this would end up being much harder.

Also If I did this again I might make my cuts based on how much room I needed to stuff the stock HengLong motors in the chassis. I was oh so close, but had to switch out the motors. Another of couple of mm and I could have got by with the stock stuff.

As I mentioned before my Panther has lots of errors, but from 3 ft away it looks OK. I just refer to it as a King Panther II.