Ok if you really want to beat a Supra at a drag strip, then it is a different story. You would really need the 2JZ Supra engine. If you would use the 1UZ V8 then it would need quite some work with turbo's, but there is also a Supercharger for the 1UZ V8 (but that means it will stick out from the middle seat
But if you just want a fast Hiace, the 1UZ might be the best. Because it is cheaper to afford, it has more power in the lower rpm, and we know it fits.
There was a guy from new zealand selling these engine mounts but it is not online. However, I think there must be some of these tuner shops in Dubai that have some experience in welding custom engine mounts for you.
I don't know much about the A45DL transmission. I'm not sure if it will hold all the power.
Since you only have rear-wheel drive, it should be possible to use the automatic transmission that also comes in the Lexus LS400 (just like the 1UZ engine).
So I think you have to find an old Lexus LS400 in your area for engine and gearbox. And then find a shop that can make the engine mounts for you.
Just call some of these tuner shops, say that the engine fits but custom mounts have to be made. And see what they say.