You'll need either access to one and/or a photograph of all sides with dimensions.You then reduce the engine to its simplest shapes i.e. a rectangular block for the main block, a truncated cone for the bell housing, all the various components are a shape or another. the idea is to reproduce each shape in scale and put them together. I built a 702 like that. Here is the thread:http://www.modelcarsmag.com/forums/topic/101332-scratchbashing-a-702/ Hope this helps.
I guess I am not cut out to do "paint over foil" . The first attempt (on another model) was a disaster and was scrapped. This one isn't much better. I think I'll stick to the 13/0 brush & silver paint.