There's no accurate megatron that fits in with universe/classics toy line so I made one and I noticed Optimus and Megatron have the same body type so I used an optimus. Switched out the head, gave him his signature arm mounted fusion cannon, a new chest, big fists (from a robot heroes), energy sword (painted hot glue) and a full repaint.
I had to sacrifice the transformation but I would have never wanted him in gun mode anyways.
Loved how he turned out. Comments/criticisms appreciated. Enjoy.