Wood floor gap between frame

[Trackman101]

I am converting a shorten long box steel bed to a short bed wood floor (a prior owner shortened) and was wondering what is the expected gap between the floor and the frame rail.With my new sills on it is flush to the frame. Am I missing some spacers? I will put my box together and see how alignment is next with the rest of the truck. Hopefully I can add some spacers to gain clearance and keep good alignment. Any guidance would be appreciated.