Such an arrangement would probably help the CoG in later Spitfires, they had a lot of ballast weight already put in the tail. However it isnt simple as most things arent. The Mustang/P-51 always had the basic radiator layout that it had, but considerable work was needed to get it right when the Merlin was installed, and the Merlin needed additional radiators for its intercooler. The Griffon would also need more work to get it right, as it needed more cooling in proportion to the extra power it made.It was a (rough) sketch/draft by Supermarine I guess. Maybe therefore it just wasn't thought through at the time. This is the first time I see this arrangement of the Spit. It apparently was not very well known. Had they follow this direction the CG issue would have been to be addressed.
I then wonder in which way.
Moving the wing, allocating balancing weights?
Btw I consider the snubnosed Spits (especially with fixed tailwheel) to be supremely ugly but most Griffon Spits (Mk XVIII and 21!) supremely cool-looking.