has he run that engine? Do you trust he knows what he is doing with running the engine?
In general at least what I recall from what the nitro guys around here and others have said, they tend to avoid buying used engines (or giving them much value at all) if they don't know the person who has used it as they could be in bad shape.
As for fan fair on the SC8e, just no real class for that for racing, maybe it will change now with that new Vorza SC or whatever it called. What I have read on it is that its a good vehicle if that is your thing.