Maybe you should've had that in bold lol
You will run into issues, no doubt. Anything can fit with enough money thrown at it, but putting a 2j in an M35 would seriously screw the excellent weight distribution among other things.
You may have a little trouble controlling the variable valve without the stock ECU I would think (again, depending on which ECU you used)
The amount of cash it would cost to put a 2j + trans (+ AWD?), you could probably buy a Crown Estate OR built up the M35's engine and trans for some pretty serious power.
Seriously, if you want a 2j that bad, sell your M35 and get a Crown Estate.