Escort EFI Cabriolet Help

I'm maybe buying an "H" reg Escort EFI Cabriolet with around 87,000 miles on the clock. The car looks nice and clean but there are a few points that
I need assistance with...
Engine sounds top end noisy (tic, tic, and tic)! How much would I expert to spend on a camshaft, cambelt, head gasket etc?
There is a small corrosion hole near the battery tray, (near the master
cylinder). Is this a common problem?
Are there any known problem areas that I should look at?
Can anybody recommend a good online parts dealer?
Finally, how much is it worth?
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