Can't say I see the resemblance David, well apart from short horns.
There was 10 main factories in the 70's. Most started out in the 50's but Terada go back to 1912. Peavey were definitely aware of them, you can see the origin of the harpoon peghead on Kawai/Teisco guitars from the 60's.
I'll agree on proprietary parts but don't see the unique features, not on the late 70's T-series.
The phase switch was nothing new. Dan Armstrong put a Spin-a-Split tone knob in his London guitars/basses back in 1971/72. Even the 'Bi-laminate' neck was old hat. Reverse grain for strength is not only an ancient woodworking technique it wasn't a Peavey first, my old Wilson Sapphire from 68 has a bi-laminate neck.
For me it's the simplicity of that single Super Ferrite