think beyond IHI if you have £7k and want >400bhp to go with 4wd
as for not worth it.... if you want something unique then it will be unique and very unusual when done if you covert an
ibiza into 4wd, big turbo it etc.
it will cost a small fortune to et it done right, presuming you will employ someone to put in the 100's hours it will take. Unless you are gifted in making & converting yourself, like Dan is, you will spend many £1000's on someone else labour costs. Unlikely to sell the finished article (if this is a short to mid term likelyhood) and recover anything like it cost to convert. Hence if its the power & acceleration you are after, eg: big turbo 1.8t & 4wd package, and not the unique 4wd of an
ibiza, combined with BT power, then a different starting point might be more prudent.
It will cost more than you think, almost always...