I know there are a lot of DIYers out there who use WD-40 for cleaning. Check out some of the other enthusiats forums and you'll see the debate going on there as well...!
I find it impressive you got the engine THAT clean. It's one of those "I just gotta see for myself type of thing"... I know some things were replaced in the engine, such as the spark plug wires, that white plastic timing belt cover? (unless some stickers were removed/replaced), so that makes me a bit skeptical as well. Would have loved to see all the original components still there to have a true 'Before and After' comparison.
Regardless, mad props for a seriously clean engine bay!