A quick update.  After working out how to force the "chips" driver to
use the ModeLine that was working fine under the old X with no
improvement (it appears to probe all the h/w correctly, pick sensible
sounding modes - but still overdrives the display).  I gave up and
tried the "vesa" driver.

The "vesa" driver does produce a correct looking display (no ModeLines
etc needed).  However when X exits, the console is not restored to
ascii mode.  kbd_mode -a doesn't work (says there is no /dev/vga - no
surprise).

Is there some other command (other than reboot) that should restore
the console?

Thanks
--sjg