Going to 18" rims questions

Sorry, read that backwards at first time I replied. I don't think a 35mm offset with a 5.87" backspace will work.
You likely can't go any more than a 4.5" backspace on the rear and 4 - 4.5" backspace on the front of a stock suspension.
You only have 5.5" from the face of the drum to the leaf spring in the rear.