[GBrutus]

Perhaps the July 1942 Merlin 61 spit could be a converted Mk Vc with the nose of a Mk VIII and the larger radiator under the right(?) wing and the later Merlin 63 spit could be Ranwere's Mk IX Mod.

Here is some info I ran across http://home.epix.net/~cap14/spit9v109g.html

Nice idea, though it would be more straight forward to splice the tail and rear fuselage of the Vc onto the VIII. Problem with this is we will be left with the aero-vee filter. I think Ranwer's early Mk IX mod would be the better approach.