The original of that article is here:
link.
I've checked out two sources listed, the 'Curtiss aircraft' by Bowers, and Ray Wagner's on-line version of his book on American aircraft. Neither mentions the 1350-1360 HP figure, that, now thinking about that, is not mentioned with regard to the altitude it is supposed to attain.
I'm not sure that 1480 HP on WER is that shabby either