So you'd need a v6 arb, shocks, wishbones? springs, engine mounts and probably a lot more that I haven't thought off.
Wishbones are OK.
Also needed are -
TB Hubs* ( best fit them with new bearings to be sure )
Driveshafts ( some are common to the V6 3.0, some unique to the TB )
Track rod ends
Air filter and housing and induction piping
Pre cat exhaust system
I don't know which TS you have, but you'll need extensive rewiring for the new ecu, probably the cooling system wiring and depending on TS year, re-siting of relays and fuses. If your TS doesn't have the M2.10.3 ECU, you'll need the cooling system controller from the early cars.
The windscreen washer reservoir may have to be moved to the boot ( the wiring is already there but you'll need to install the plastic piping ) if you use the proper GTV TB induction piping. Also, if you're using the TB ECU, you'll need to reprogram it for your CODE box.
You'll also need to look into the fuel vapour recovery system, brake servo vacuum pipe.
The GTV/Spider TB has the intercooler behind the bumper and in the empty space in front of the wheel arch liner on the left side of the car. You'll probably need to look into using that system to avoid massive surgery to the front crash crossmember of your car to accomodate an intercooler there. See the Turbo conversion thread by forum member turbonutters for details on the front end modifications necessary to site an intercooler across the front.
There's probably more, but you'll need to do a massive amount of research with things like ePer to determine what is different between the two cars.
* look into the possibility of using V6 hubs and shafts and then you can use the V6 305mm disks and Brembo calipers