I fully understand and apreciate the sentimental value the car is but I have to agree with Ginge on this one I think. Along with all the unknowns on your list easily costing a few grand it sounds like its been stood for a long time and will need mechanical repairs too. Have you factored these in because that can be from a few hundred quid for a good service to a couple of grand depending on what needs doing.
At a guess it may need all four wheel bearings, suspension bushes, ball joints, brake components, engine work perhaps?
And once its all done and you start driving it you'll spend ages faffing trying to sort out the niggles that crop up when a car has been sat for a long time.
I honestly think its too much hassle and expense for what you'll get out of it.