Hi Cian,
Here's a project I worked on before that you might get ideas from. An MR01 chassis with excess plastic gutted out just like yours. I made what looks like a big h-plate to keep the radio gear in. I managed to fit in a caseless Hitec Shredder and "flattened" ES-01. For the servo, I used a GWS Pico servo with the mounting supports removed. This thing ran pretty good until the M24 Mid arrived-- which was what I was trying to make this thing into
.