Kind of embarrassing how simple the question is but when it comes to vectors and Cframe, they're my worst area of expertise. Thanks for the help.
Put this in a part
script.Parent.Orientation = Vector3.new(0,0,-180)
In a script in the part:
script.Parent.Orientation = Vector3.new(x,y,z)
x,y,z stand for the new rotation (probably 0,180,0)
workspace.Flip.CFrame = workspace.Flip.CFrame * CFrame.Angles(math.rad(180),0,0) -- use math.rad for every angle