I don't know if this will help or hinder things. I have two 1981 Kuwahara BMXs (one frame still has original Kuwahara stickers but they have worn off the other) in Australia. The serial numbers on both begin with M1F followed by 5 numbers which is in line with stabdard Kuwahara BMX serial numbers at the time, except that they don't begin with K (Kuwahara built) or T (Tange built). I don't know what the M represents.
The odd thing is that they are both fully lugged CrMo frames rather than welded as was standard for the Kuwahara and Tange made frames. For example, if you look at the dropouts they are identical to the Apollo lugged dropouts yet have the double gussetting and serial number positioning of the KZ-1 frames (very different to Apollo).
Now, I have two of them, yet cannot find a single picture on the internet that look the same as my frames. Is it possible that Apollo made an Australia-only Pro BMX frame for Kuwahara to look like the KZ-1 only using their own lugged technology?