Bob,
Unless a fellow lister chimes in with an offer for the upper rails, you will have to look at autojumbles, ebay, for sale ads. The wood packing strips can be made. They were about 1" wide and at the front 1/2" thick tappering to about 1/4" at the rear and just long enough to allow for the front and rear bolts to pass through with about a 1/2" pass the bolts. Any hardwood, oak, elm, etc will do. Upper seat rails from a Mk-II Sprite or a Mk-I Midget will work with the Bugeye seats as they were the same.