Is this an effective way of creating a random box?

Here is the script:

	local ranGen = Random.new(tick())
	local lSPC = 1
	local rSPC = 2
	local uSPC = 100
	local oSPC = 350

	local function randomBoxChooser()

		local ranNum = ranGen:NextInteger(1, 1000)
		print(ranNum)
		if ranNum >= oSPC then
				
			return "Ordinary Box"
				
		elseif ranNum >= uSPC then
				
			return "Uncommon Box"
				
		elseif ranNum >= rSPC then		
			
			return "Rare Box"
				
		elseif ranNum >= lSPC then
				
			return "Legendary Box"
			
		end
		
	end

I originally had a for loop going up to a thousand and putting in names of the boxes based on probability but that seemed really inefficient to me so I changed it. Just wanted to know if this was the most efficient way. Also later on I Clone the box into workspace at a random CFrame. Now I have read an article on how we should set the parent last and was wondering if that applied to CFrame as well. Here is an example of what I mean:

local box = serverBox:Clone()
box.Parent = game.Workspace
box.CFrame = location

Hope you guys can help. Thanks!