Hi Andrew,
I have just stumbled across this thread while doing some quick research into another chassis. It caught my attention as my grand father, Tony Mitchell, owned this car many years ago.
As someone who frequents other historic forums and is involved in historic motorsport, I understand the feeling of completion that will likely occur when I am able to fill in some gaps for you!!
When Tony bought 1001 c.1974 it was painted yellow, with wide arches and what he describes as "Wolfrace"/6 spoke wheels fitted. It was bought for £1700 out of Exchange and Mart from a coal merchant in the Kent area. The deal was completed as the previous owner wished to keep the race wheels, and there were some original Borrani wire wheels which came included, which were promptly fitted.
However, with these narrower wheels, the wide arches on the rear looked very odd. So the rear bodywork was altered to have original size arches again, and the colour to Blue.
While the body was away being sorted, the race spec 289 was removed and a new 289 with Holley carburettor fitted for ensured reliability for use on the road. The race engine then remained under a bench until c.1979 when it was sold on to Vince Woodman for £300 complete, for one of his Capris.
1001 was in his ownership for 2-3 years until he sold it to one of his customers, Steve Stevenson. It was still looked after by Tony for many years after this, until it was sold on, and on selling it a long story ensued!
While Tony owned it, 1001 saw much use, even taking my Dad to school sometimes - safe to say he became quite popular. Most of the usage was on the road, including shooting trips. One time it was taken to the Pomeroy Trophy at Silverstone. Soon he found that being quite tall, by the time he had a helmet on the door wouldn't close! As time was of the essence, the bottom of the seat webbing was hastily cut out with a Stanley Knife!! It turned out to be a waste of time as after two laps the race was cut short due to snow! Having driven the car to the circuit, a trip to the Green Man warmed everyone up.
He has had many interesting cars over the years, and the stories are fascinating!
I hope this helps you fill in some gaps with the story of the bodywork. I'm also pleased to hear that you are not trying to recreate 1001, as this car is very much still in existence.
Ben