If it's a redtop engine you mean then you'll need all new mounts, driveshafts and hubs, you'll need to strengthen the chassis, upgrade the brake discs & calipers and pads and also suspension, also need to get a custom exhaust system made up, and depending how you obtain the 2.0LT you may need to re-build it as these engines are getting on abit now!
But these all come in nice easy to buy off-the-shelf kits
http://www.chrisastleymotorsport.co.uk/
I recommend that guy to get the parts anyway.
And also i'd ring him, and make him aware weather your car has PAS or not as that will effect what type of mounting kit you have