Adjustable Pedal box details wanted

[Ronart boy]

Can anyone help me, I am building a MK1 Ronart W152, which has a fixed pedal box, but to be able to make the car more usable for other people I am wanting to replace the fixed pedal box with an adjustable one so differing leg length can be accommodated.

I have read that certain Marcos models had such a box. Could anyone provide me with details of how the box works or photos so I can make one to fit in the foot-well of the Ronart. Even better would be to see one in the flesh so to say, I live near York if there are any owners nearby I would be happy to see the box in your car.

Does anyone know if the adjustable Marcos pedal box can be bought

Thanking you for all reading the post

Howard