How can I make this morph size properly?

So I have a morph of a warhammer space marine, and it works. The problem is that it's bigger than the character, and it doesn't morph correctly. I have no idea how to make it so the character gets sized correctly for the morph. Can someone help me? Also, there's literally no size script because it was meant for normal characters, and I'm script illiterate. https://gyazo.com/4dbe95c3e4381e0aeaa22ecbf8a819cc

I don't have your script, so I can't exactly help you. But, if you want so shrink a model, this will work. Make sure your model has a primary part!

local scale = 0.8 -- how you want the size to change. A value of 1 will yield the same size.
local pp = script.Parent.PrimaryPart.Position
local parts = script.Parent:GetChildren()
for i = 1, #parts do
	local focus = parts[i]
	if focus:IsA("BasePart") then
	local Vec3size  = focus.Size
	focus.Size = focus.Size * scale
	focus.CFrame = focus.CFrame * CFrame.new((Vec3size.X- focus.Size.X)/2,(Vec3size.Y- focus.Size.Y)/2,(Vec3size.Z- focus.Size.Z)/2 * Cframe.new(pp)
	end

This is the best way to resize a model.

If it is made out of unions you COULD export it as a 3D Model then open it in Blender or something to resize it down. Import it back into Roblox then increase the size of it. This should both help performance of the game due to CSG being a main cause for lag in most games and also look a tad more polished and you could texture it if you wanted to.