Very reasonable if your using Raduino or other digital signal source for VFO and BFO.
The very original BITX was the BITX20. So ther eiss a schematic for that and you can
get the bandpass filter and low pass filter from that.
The two big things are the band pass filters and replacing the low pass filter.
Of course the Raduino sketch has a few changes as well (set up the correct frequencies.).