http://www.ecihotrodbrakes.com/early...nversions.html
You will have to get some 42 squareback spindles for a 40 as the brackets are designed for them. Kit is $160 plus cost of calipers and rotors which are very cheap at Autozone or others and the price of postage is high.
I had the same kit on my model a for a while. It is now on my 36.
https://sites.google.com/site/mrtexa...ydraulicbrakes