You can pick up an engine for about £200 but you will need to take it apart and check and measure everything. If you can buy a complete car that you can here running that is rotten or has been smashed up. There's a lad up in Scotland who breaks them, that will do a full set-up for you for about £600 ish inc postage I've used him for some parts for my conversion that I currently on with and he's dead reliable.

You will need:

FUEL PUMP,
ENGINE,
TURBO,
WIRING LOOM + RELAYS
INTERCOOLER,
RADIATOR,
AMAL VALVE,
DIZZY,
CHARGE PIPE,
FUEL ACCUMILATOR.

I'm sure i will have missed 1 or 2 things off but someone will say something.

Cheers
Dave