OK, this just occurred to me. If I mount this chip in my 1.0 XBox and boot off it (the bank that works) It shouldn't FRAG. It's a 1.0 XBox after all. Then I flip the switch on the chip and flash it with the x2_5035 New bios. Take the chip back to the 1.6 box and boot off the second bank.
I'm an idiot, but I'm thinking (in my limited noobie way) that this just might work.
Now I just need to find a pin header to install into the 1.0.