By dumb luck the PTCs I ordered on Ebay were PPTC, if the description is correct.
I video-ed the surge. The 1st Speedy(Arduino EFI) is the one with the blown traces, but I also test my other Speedy at the end. Just under the 5.31V is the amps, with the DMM showing the amps across the blown 32mil trace, the only GND for the Arduino side, and is where I want to put the PPTC fuse. I was using the MEGA with the blown USB IC, but it should be ok because I compared it to a good MEGA and they both surged to 70ma and the settled to 50ma.