Shed for swallows

Hi all, I hope I can get some advice. I have a little shed in the garden (roughly 8x4 ft) and the ceiling is around 7ft at its highest. 

Would this be a suitable place to place a swallow nest box? Fortunately the shed is hardly used so they wouldn’t face much disturbance and the door doesn’t close properly so access should be easy enough!

Other than the height, my only concern is that we do have a lot of local cats that visit the garden. Should that be a worry? Or can I trust the swallows to make a judgement on the safety of the location before they occupy the nest box anyway?

Thanks all!