I HAVE BEEN OFFERED ONE

DO U HAVE TOO CHANGE OUT TOO FIT IT ?

DO U HAVE TOO CHANGE THE PISTONS

IF SO WHAT DO U USE ETC

 

If it's a complete engine it should have the pistons etc there mate, surely ? Provided it's a 'sound' engine it should be fine and go straight in. Given the different physical dimensions of the block there's a possibility you may have to fiddle with the engine mounts but other than that in she goes. Make sure it is a turbo engine, not a naturally aspirated one as the compression ratio will obviously be different for them both.