Solved -PJ655- Dennis Adams' proposal for a Tojeiro's Corvette-engined GT, 1965

[nicanary]

Was the driver who commissioned this car best known for driving large American-engined cars?

[Paul Jaray]

I had a quick look in my index and (if I'm not mistaken) he used all British engines.

[mekubb]

Chapman ?

[Paul Jaray]

Nope.

[Otto Puzzell]

Healey?

[Paul Jaray]

Nope.

[Otto Puzzell]

Lister?

[Paul Jaray]

Not Lister but closer.

[oko94]

Ralph Broad of Broadspeed fame ?

[Paul Jaray]

Not him.

[nicanary]

Eric Broadley?

[Paul Jaray]

Not him...it won't take much

[Otto Puzzell]

Raymond Mays?

[Paul Jaray]

Not him.

[Otto Puzzell]

How about John Cooper?

[nicanary]

Ken Nicholls?

[Paul Jaray]

Not Cooper or Nicholls.
Cars were named after him, like Cooper, and sometimes after him plus the engine, like Cooper.

[nicanary]

John Tojeiro?

[Paul Jaray]

Yes!
Now, a big clue for all.
You can find a big help in finding the man who did the design...if you look closer at the car, there are about 2 styling clues that should lead you to him!

[nicanary]

One of the Adams brothers?

[Otto Puzzell]

A very young Frank Williams?

[Paul Jaray]

One of the Adams brothers?

And now, the final bit of tihs intricated story: Tojeiro asked Dennis Adams to design this Corvette-powered Gt to use one of his old chassis he designed for which, unfortunate, gt?
Point for nicanary, but anyone can have a go

[nicanary]

Britannia?

[Paul Jaray]

And yes!
This is the clay model made in 1965 by Adams of the nicknamed 'Corvetra', an improved Cobra with a Corvette engine.
A well deserved point for you!

[nicanary]

I have checked UK Google both text and images, and there is nothing about this car. It's definitely not something I knew about, and I only solved it using your excellent clues.