I had the same problem in Queensland so i went ahead with a CADET conversion.
A ca half cut is much cheaper and you can spend the money on the turbo and/or management if you really want it to go.

To give mine more stick im running a ball bearing turbo off a rb25 and its nice and quick with boost coming on about 2600 rpm and pulling like a bitch to redline. However i usually shift 5500 to 6000 to be nicer on the motor.
This conversion will spin 1st and 2nd on 7psi boost. Its also done 170 km/h effortlessly on this boost. Its getting good economy with a bit of strapping out of a tank.

It s getting wound up to 14 psi in the next week or so and should be alot more fun. But i dont expect the rear tyres to last more than about a week. Ill be using a dual boost controller to be nice to the motor when im in the mode to go quick and not stupid quick.

The ca is a good conversion and you should be happy with the results

I have the turbo off an RB25 on the ca18 in my 1200 or at least i thought i did. Have pulled it apart to put new seals in it and have found that it is a ball bearing turbo and it is perhaps bigger than i thought. It makes the original t25 turbo off the ca look minature. The funny thing is the bigger turbo starts boosting at about 2400 and has full boost at 2800 to redline. Any ideas where i could get the specks and model number for this turbo. And the exhaust flange is six stud instead of the usual 5.

You can fit a silvia turbo 5 speed gearbox with no tunnel modes except for the moving of the shifter hole.

You have to get a clutch system made up to run hydro clutch.

Custom mounts need to be fabricated for the motor and the gearbox. Engine mounts need to be moved foward 40mm and the the shifter come out just near the end of the seat.

There are guys in brisbane that can do this, almost any shop experienced in engine conversions should have no problems