found some more info:
"The 1979 Phil Read Replica based on the Honda CB750 F2 engine SOHC in-line four cylinder 4. 150 Phil Read Replicas were prepared by Colin Seeley for Honda as a special run.
Former TT rider and frame builder, Colin Seeley, was commissioned by Honda to celebrate the success of the Isle of Man race bike. Ironically, the year it was released, Phil Read was beaten by the returning Mike Hailwood on his Ducati. That victory proved a turning point for the marquee.
Only 150 replicas were built by Seeley and very few exist today, mostly within the UK. There is a Seeley Honda that people often get mixed up with the Phil Read replica but that used a full Seeley-build chassis and was popular with the touring brigade, whereas the race-rep is merely a standard [[Honda CB750|Honda CB750], stripped of its tank, seat and exhaust before adding UK-built Seeley items and a fairing. They even left the original side panels on to match the rest of the scheme.
The large megaphone has a much sharper bite to it than the weak-sounding exhaust system on the original CB750. Finding genuine parts is near impossible!"