VFD and Varispeed Mill Heads

Is there anyone out there who would like to comment on the potential
for converting varispeed milling heads as found on BPs etc with a
direct belt drive (removing variable pulleys and fitting a timing
belt) and retrofitting a VFD to control spindle speed. This used to
be done with chipmaster lathes and led to a much quiter drive.
Thanks
Fred

All for a nice quite workshop!!