Note...They are set screws, not set pins, in this location. Set pins are used to locate the pivot blocks on the car. Easy to confuse.
With the pivot blocks in the low positions, you probably can get by using the 4-40 x 3/16" set screws to limit up travel; however, when using the pivot blocks in the high positions (and/or with additional spacers) you need 4-40 x 7/16" set screws as shown in Step C-02.
Hope this helps.