Absolutely gorgeous car! I don't even want to know what you paid for the car, but I can tell you that you own one sweet ride.
To answer your question you have to answer this question:
Do you like the way the car handles presently? If so, don't change it, you'll be cutting up a very nice finished job, not modifying an existing project car. Perhaps after some time has passed and you think you want a little more out of the car, like more hp and handling, wider ties, and so on, then do the mods, otherwise keep it the way it is--remember, it is finished very nicely right now.
That said, all things being equal, I would opt to modify a Scarab-type of engine mount (which this is) to the JTR version. However, with a car as nice and as finished as this one is, drive it around and see if you like it. If so, do not touch it. Also, if you can drive someone else's JTR Z to compare, definitely do so. You may (or may not) be surprised. Food for thought.
Davy