Best Process for making a 1985 Jaguar XJS HE road ready after 13 years of ?

I was recently given a 1985 XJS HE V-12, with less than 70,000 miles. The last inspection sticker indicated 1998 so I assume that was when it was last driven. When removing from storage one of the windows was down a couple of inches so I put a battery on and when I turned the key on all the lights came on and the window rolled which was encouraging. What is the best way to go about making the vehichle road ready again, engine wise? I have been given many suggestions but would like to try and do it myself and as cheaply as possible. Drain and replace all fluids and filters, etc...... any help will be appreciated. The body is in mint condition although it will require a paint job