It's easy to see how certain arts may have influenced other styles, when forms are borrowed from. What one should keep in mind though, is that many Okinawan practitioners/sensei have borrowed several concepts, theories, & principals from more than just one Chinese based system.
I agree that there is a great similarity in the above mentioned wing chung form and Tensho kata. As far as that making Wing Chung the base for Goju Ryu, though, I have to disagree. Was it an influence on certain aspects of Goju? Most likely. But the same can be said for Pa Qua, Sing Yi, Ngo Cho, as well as a few others, I'm sure. Will we ever know for certain, what, if any, style was the main influence for the style we call Goju Ryu, today? Most likely not.
I can say, with certainty though, that Pa Qua Chang and Sing Yi had a big influence on the branch of Goju that I study-Meibukan Goju Ryu. It was founded by one of Chojun Miyagi's senior students, Yagi Meitoku. Dai Sensei Yagi would take periodic trips to China (along with his pupil- my teacher-Ikemiyagi Masaaki) and study Pa Qua & Sing Yi. I believe these styles greatly influenced his teachings of Goju. The very fact that the Meibuken kata that Dai Sensei created and added to the curriculum, are named after specific aspects/animals from the Pa Qua teachings, speaks for itself.
My own teacher, Ikemiyagi sensei himself spent time abroad studying other syles outside of asia, in order to get a broader understanding of his own style. He looked at/trained in boxing, jujutsu, capoirera... Did he incorporate everything that he learned? Obviously not, for then it would no longer be Goju. The basic underlying principals that make up a system must remain intact in order for it to continue as such.
If one wishes to find the origins of a particular style/martial art, then one should first take a good, hard look at its basic principals/teachings and, if it (the principals) has not drastically changed since its (the style's) conception, then you may be able to find a connection between it and some older style with similar principals.