Yes, new clutch and flywheel.
Crossmember and tailshaft will be wrong as the box has to move forwards (as I said by the difference in input shaft length between 6cyl and V8 aussie 4spds).
Go for the V8 commercial diff as you'll need to swap tailshafts or get one made, so best to do it now than later. Talk to CRS or Dellow, as I said one of these conversions (6cyl or V8, can't remember which) uses a standard tailshaft with a special yoke, might be the V8.
Don't be too concerned about what donor car you get, just grab one with the best engine and other bits you can use (like say a GTS dash). You can pick up a V8 ute, van or tonner (can be 6cyl tonner diff as they are the same) reasonably cheaply. Tailshaft is the same as V8 statesman or wagon or ute or van with 253 or 308 manual or 308 trimatic or 308 TH350 (just not TH400). Tonner diff will need adapter uni but these are cheap. I always reckon it is better to pay good $ for a good car for a donor, that way you can always sell off good panels, interior etc and the bits you want are normally better too. You'll pick up a pretty good 308 powered HJ-WB for under $5k. You may even find one with a Supra box in it already, and sell your whole engine and box off.