Nice pics Mark.
I checked this bike out at CD5. This bike is slightly different to standard. Pipe is modified to be more tucked in. Forks have steel F4 sliders unfortunately, not spiffy turned down alloy ones of F21M (long before RHs & YZs had them)
I actually prefer the looks of the 2nd model F21M in green & white. The first-bike to carry the greenstreak name & the lime green colour which became Kawasaki's corportate colours.
Believe it or not the F21M frame was claimed to be chro-mo, way back in the 60's. No doubt japanese chro-mo, but I have felt the weight of an F21M frame & whatever it's made from, it is very light.
Its often claimed that Suzuki had the 1st jap production mx w the late 60's TM250, but I think Kaw beat them w the red F21M the year before. Anyway Kaw had already produced the B8M (125 I think) prod'n mx-er in mid 60's, which was actually piston-port not rotary valve.
Those early rotary valve engines were very wide - just how wide doesn't really show up in photos. And that F21M engine in the American Eagle Geronimo also made a very nice bike. AS I recall Brad Lackey rode one of those for a while.
Kaw were decidedly different to other jap bikes back then, tho the later MXers bore considerable resemblance to Suzuki ones (I wonder why, Mr Pettersen!). They have always been rarer too. Sadly Kaw has too often been somewhat half-hearted w their racing effort & it shows in their results & consequently their production numbers