allband version

I have investigated the possibility to build an allband version.

A device Si570 could be used to generate all signals. The CB set can be set to a fixed frequency. A microcontroller, LCD and rotary encoder can be used to control the Si570.

It should be possible to build one for most HF bands. However 28 MHz will be difficult. The Mixer will leak some 27 MHz. A suppression of 40 db is possible but it is hard to accieve. The 28 MHz bandpass filter won't provide enough attenuation.
I think that 24 MHz will be difficult too.

For 14 MHz and higher a preamp between the mixer and the bandfilter may be needed for reception.

Using a Lo signal that is higher than the reception frequency is needed for bands > 10 MHz. LSB and USB will be switched. I better use it for all bands. it will reduce software complexity. An additional advantage is that the Lowpass filters can be used to reduce mirror image reception.

80 meter version

The design can be adapted to 80 Meter. making a suitable LO signal may be a bit difficult though.

Two 23.5 MHz xtals are required (27-3.5). These are non standard as far as I know. 30.5 (27+3.5) MHz can be used instead. Those are nonstandard frequencies too.
using 30.5 inverts LSB and USB.

23.5 MHz can be generated by dividing 47 MHz by 2. You could try to use a VXO at 20 MHz. Then double this signal and mix it with 7 MHz.

A band 300 KHz wide band filter for 80 meter can be found in the Elecraft K2 design.