Yuck! I'd have to sort through hundreds of lines of other irrelevant code. Plus the disassembly listing doesn't appear to assign symbol names to the registers, making it unintelligible. It appears that it's easier just to look at the register view in MCC, and write my own code to set them to the values that it produces. Too bad they don't support assembly language.
For this project, it looks like the 1703 was not a good choice as a retrofit for the 630 after all. I'd thought they'd be a drop-in replacement hardware-wise, but I'm starting to see more problems that will likely turn it into an enormous job in addition to the whole register configuration problem. I think I'll save the 1703's for some other project.