What 'level' would you like to point out on the Matchless?
My 'carbon copy' comment was more biased toward the misconception that there must be some kind of flat line along to bottom of the tank and seat base. Stupidest BS I've heard (continually) in quite a while pertaining to bike....I've heard dumber stuff but it's usually related to politics or religion.
So...point me to this 'level you speak of....
Perhaps if there was an emblem on that gorgeous alloy tank posted above it would 'look' level? Personally I think it looks pretty damn smooth. I do think you should try to recreate the back of the tank in your seat cowl as per the photochop, so sweet looking!