depends on what you do your self but a good 300 + gearbox ,rad/intercooler ,exhaust,pas pipes,etc,labour,£2000 ,might be cheaper to buy donor and swap it your self engine loom unplugs at back of pedals
I believe an 'ES Premium' is a disco two as the one was just a 'Premium', therefore with the electronics involved it's not that simple to swap engines and even more involved if the V8 is an auto.