'orrible thing: should have spent the money on developing the Sea Hawk faster.....
However, ideas:
1. Turbofan close support aircraft. Replace the Nene with what amounts to a non-vectored Pegasus, i.e. an Orpheus core with Olympus fan stages on the front of it. Hack the rear fuselage about to make it look like the back end of an A-10 nacelle, i.e. a hot pipe in the middle of a cold duct. Fit a Swift-style nose with a nosewheel. Getting appropriately positions main wheels will be difficult with the exisiting wings: my quick'n'dirty suggestion is to replace them with F-84G ones, wihch have nice tip tanks and nice, self-contained gear bay, thus leaving the centreline free for ordnance. Guns can either go in the nose or under the intakes, Swift style. You could even go for STOL capability by claiming that some of the fan air can be ducted down the wings for Buccaneer-style wing blowing.
2. Turboprop close support aircraft. On the other hand, since it's got a tail-dragger undercarriage, why not work with it? Make it into what amounts to a mid-engined Wyvern, with the big turboprop in the centre fuselage driving nose-mounted contra-props via a P-39-style drive shaft. Wings and guns could stay where they are...