Hurrah! I have figured it out. Sincere thanks to everyone for the suggestions and help. It is truly a pleasure to be part of such a supportive community.
Here is what happened:
The keys are the following two statements from the release notes for 2.7
The theme for v2.7 is make TC/MC easier to use by promoting a single extension installation method (mount) while still supporting copy into filesystem.
* Renamed tcz2ram.flg, tcz2ram.lst to copy2fs.flg and copy2fs.lst, use flag for all, or list to specify extensions to be copied into filesystem.
I have always without much thought had all extensions loaded to ram rather than mounted. When the name of the "load to ram" flag changed, my boots attempted to mount all extensions rather than load to memory. Unfortunately, the number of extensions exceeded the default mount limit. So the extensions did not mount and the boot failed with the various error messages I was seeing (depending upon exactly how many extensions were in the tce directory).
Either increasing the mount limit via boot cheatcode or using the copy2fs.flg work. So, back in business. Makes perfect sense after the fact as is usually the case but made for an interesting morning.
Again, thank you to everyone for the assistance.
Best regards,
sci_fi