Ok, so after a few adjustments, there is now a working MSX version.  

Buleste has built the 2nd ever unit, and made a few adjustments such as using an I2C lcd screen, and easily available lm386 amplifier module (so it's now more mainstream and less Frankenstein!).  The major advance has been with the WAV file generating software.  Using a modified cas2wav program a golden sample rate has been found, and no extra adjustments to the Wav files are needed.  

I have also modified UEF2Wave, a python script which generates wav files from a UEF, so it gives the same output (and to save my time, will convert all UEF files in it's directory to WAV files).