The narrow string spacing was used more often on 6 string basses of the time.
I happened to try out a Bass VI in a shop yesterday, the spacing looks awfully similar. Will take some getting used to, for sure. (Otherwise, that Bass VI wouldn't really compare to a Series II, now would it?)
The backplates look to be a perfect fit, and there's quite a number of holes to drill. And I seem to remember there was a great shortage of chrome-finished toggles for a while, so the extent of the repair might be a replacement of a toggle switch that went south.