There arn't any good line drawings for the Spit that I know of.
I have lots, but same old story, lay them over the top of each other and not one lines up with any other. Go to Airliners.net get as many profile photographs as you can and take your best shot at making your own.
I'd be interested in checking your resulting shape next to mine when you are done
Click my sig to go to my construction site then check out my Mk V's on there, remember Mk IX is really an up engined Mk.V airframe.