In this order approximately:

-Money

-Engine complete with all ancilliaries/plugs/DBW throttle pedal

-Gouky engine mounts

-Gouky manifolds

-Turbo LSD gearbox and shafts

-Custom Y section to chosen backbox

-Turbo or Walbro fuel pump

-FPR

-Decent donor car

-Loads of little fiddly bits you didn't realise you needed until you get stuck.

-Lots of patience with the electrics

-New pants when you floor it for the first time

Twobrutal is your best bet for info, but as Luke says the major hurdle is sourcing an engine.

The rest of it is no more difficult than the rest of the swaps.
