Youre ready to throw in a new valve block and you dont even have any known symptoms yet? I see you have gone with the "throw some money at it" approach..
Good luck, I really hope it works out for you. Many people before you have put in brand new valve blocks and still not have had any change in their problems (such as my own issue with the fronts dancing). Probably best to get your car back and get to know it a little better until you can notice some consistent symptoms. Then maybe someone here can really help you out; instead of just plain guessing
For example, something like corroded wiring can be fixed in a half hour and a couple quids worth of wiring and heat shrink. And that wont fix itself by changing out new valve blocks how ever many times you want.