Good to see an excellent fit for the landing skid mechanism.
Lead shot.. If it really is lead (rather than one of the replacement substances now quite common) do try to coat the shot in something before sealing that box. I haven't experienced it myself (never used lead as a weight) but you do hear horror stories of the lead reacting, creating a crystalline substance which expands and can force a fuselage open..!
Like I say, not experienced this myself, but coating the shot in PVA should seal it from the air/moisture and save possible horror down the line.
I use wheel lead (you know, the stuff which is self adhesive used to balance alloy wheels) and never experienced anything similar.