How do you size a mesh in a dropper script?

Hi guys you could help me with a tycoon problem, that is I have a script and I should put the mesh and everything is fine, only the mesh size is too big and I don't know how to do it, I tried everything I replaced also part.size and I put mesh.scale, but nothing! Help Please! This is the script:

wait(2)
workspace:WaitForChild("PartStorage")



meshDrop = true
--------------------
-- Mesh Settings: -- [If you want a mesh drop, set meshDrop to true up on top.]
-- Look at the mesh properties and change the inside of the quotes below to the appropriate
-- full link or the rbxasset:// style, doesnt matter which one you see in the mesh you want

meshID = "rbxassetid://3463051115"  
textureID = "rbxassetid://33533210"
--------------------


while true do
    wait(1.5) -- How long in between drops
    local part = Instance.new("Part",workspace.PartStorage)
    --part.BrickColor=script.Parent.Parent.Parent.DropColor.Value
    --part.Material=script.Parent.Parent.Parent.MaterialValue.Value
    local cash = Instance.new("IntValue",part)
    cash.Name = "Cash"
    cash.Value = 1 -- How much the drops are worth
    part.CFrame = script.Parent.Drop.CFrame - Vector3.new(0,5,0)
    part.FormFactor = "Custom"
    part.Size=Vector3.new(3, 2, 4) -- Size of the drops
    if meshDrop == true then
    local m = Instance.new("SpecialMesh",part)
    m.MeshId = meshID
    m.TextureId = textureID
    end
    part.TopSurface = "Smooth"
    part.BottomSurface = "Smooth"
    game.Debris:AddItem(part,20) -- How long until the drops expire
end