Very interesting indeed..it actually shares a lot of details with my Donohue that I've (shamefully) still not really pushed on yet with! The rear triangle is very different though on the two Donohue made Formulas that now grace this site compared to what I have.
The most interesting thing to me is the frame number though...my own frame has serial number 124689 and this one looks like 133789 (?) I'm guessing that this may have been made shortly after my frame? Plus there's the neon orange paint that I found under the paint on mine..perhaps they were produced at a similar time?
Either way I'm keeping a close eye on this, I
need some quality inspiration