I put a post on here probably 8 years ago on fitting aero screens. I took measurements with the dash dropped of where the wood is under the metal. I too drilled through the leather. I used Simmonds mounts but I don't think you can get them now. Be careful of the distance of the wing nut on the aero screen & the windscreen. Sods law says that it will touch the windscreen if you aren't careful.
I bought the folding screen kit from Hearts of England. It is best to remove the wiper blades fully before folding down.
You will also need a scuttle mounted mirror.
