The first problem I see is the squadron codes, as the combination of two letters represents a specific squadron, and there were no mixed squadrons of Hurricanes and Spitfires. If historical accuracy is not important to you, then it's your call.
Roundel sizes did vary, but they followed a size chart, along with specific locations, and it was not allowed to encroach onto the control surfaces whatsoever.
I think the fuselage and underside wing roundels should fit, but on the upper wings the Spitfire usually carried much larger roundels than the Hurricane as the latter had a much narrower wing chord. If it is the Tamiya Spitfire Mk.I you are considering, I do believe the kit includes two sizes of upper wing roundels, so you should be ok there.
regards,
Jack
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edit,
so scratch the spiel about codes, as that particular Hurricane did not sport any? Also, my suggested Spitfire kit won't do either as you want the later style roundels with thin yellow outlines.