I actually dump VSMs using a TMS5200 and TMS51XX setup, so they take care of the dummy reads, maybe its why I didn't see those. Note the TMS6125 are little more fiddly to dump
Using the '5200 and '51XX, you don't have to level-shift either, do you? I first thought about using a couple of 4066s, since I have lots of those and didn't need a lot of speed. But then I remembered that it takes VDD-1 volts to turn the 4066 switches on, and my PIC couldn't get there. I dug around and found one 4504, so I simplified the circuit to use fewer than 6 IOs. I wound up just using 3, so I could have just used 3 transistors, but this works.
I had the Vowel Power module apart to dump it, and I goofed up and plugged it into the S&S incorrectly and it looks like I fried it. It now drives ADD8 high after initialization, but then it's low for every bit. I'm not sure if I plugged it in upside down (the module's connector only has pins on one side, but the PCB has pins on both) or if I offset it one pin left or right (the PCB has more pins than the module, and the module case has protrusions that align it correctly). I was going to keep it, but now it gets the blowtorch.