I replaced the straps with chain (double jack chain), as the Westfield straps would streatch in our California summer heat, making them useless. Leather is better. You can find leather suitable for this at a good fabric shop or auto upholshtery shop. Chain, you can find at a hardware supply.
As for the pedals on the LHD cars, you can't move them. You can put some blocks onto the pedals, but the best way to deal with the pedals is to move the seat.
I am 5'5", and I have to streatch to reach the pedals. I have padded the seat so that I can attain a near perfect "Lotus Position" of a nearly reclining driving position freminicent of the Lotus 24/25 F1 car. I find that this is comfortable, and allows me to reach the pedals.
When I picked up my car, I knew that I didn't fit, so I stopped off at the upholstery shop, and piced up a thick (5") piece of padding for the seat back that moved me forward enough to reach the pedals comfortably. This is still my solution to the problem, now using padding made of three layer Tempurfoam (memory foam), with a different memory foam seat bottom. Not pretty, but very comfortble, even for 500 mile days.
Does your W11 have flat alloy floors, or the dropped floor? Does it have a bucket seat, or a seat bottom that rests on the floor, and a flat seat back?
My persoal car is an early model with the fabricated pedals and flat floors.
I will try to place an imagte on my Westyxiownersbuildersdrivers site of my seat solution and the door chains for you.
https://groups.yahoo.com/neo/groups/Wes ... ivers/info
Find the Photos, then Albums section and check out the W11 RHD Build (starts with a picture of the crate on the trailer). This is a complete build of a RHD model. It has all the detail images that you need for servicing your W11. If you need anythign else, let me know and I can supply images of my car to cover any details that you might need.