If the engine is in good condition don't mess with it. However, u can add K&N airfilter, 4 tip plugs, intercooler, down piping etc. etc.thingys to it.
Also, get whole of its suspension redone; change bushes, ball bearings, axle joints etc. etc. Get hold of a good electrician and bring all the lights, meters etc. to life. Then u can get the denting, painting jobs done.
The best tactic would be to complete one thing at a time. 1st, go for the entire suspension job. Then the electrician. Then denting & painting. And lastly, slowly and gradually, u can go for add ons like exhaust, down piping etc.
By the way, is this the same Mark II which is in Lhr? If yes, then I were also very seriously contemplating to get hold and restore it to its previous glory.
In my opinion, the whole project won't cost you a penny more than Rs.100k.