If one were to be building an RX around a scrapped Xtal filter,
that would certainly resolve the SSB bandwidth requirement,
but what of CW?

How about then using one of the USB / LSB CIO Xtals as a
crystal-plus-phasing control to circumvent the paying out
of shekels?

A bit fiddley in the switching from USB / LSB / CW though,
but the other CIO should be VXOable to pull it into range.
(ISTR that VXO statistics suggest a shift of 1kHz per MHz
should be possible)

(Train of thought triggered by a pile of bits left over from a
scrapped FTDX560 from 30 years ago, and an IF frequency
of 3.18MHz.)