I like
Leon (people don't really think Trotsky when they hear it, do they?), I think it's a lot better than
Leo!!!
Leo has a NN feel to it (and is tied to DiCaprio now), but
Leon is a real name that works on many different levels.
Maybe
Leon AndrewLeon ArthurLeon Konrad /
ConradLeon CurtisLeon DarrenLeon DeclanLeon FranklinLeon HowardLeon MartinLeon PatrickLeon RussellLeon SamuelLeon SebastianLeon Spencer
Jack Rowan sounds ok, but I can't say I like it.
Jack is a NN, I really prefer
John as the given name.
Jack Alexander I don't like at all.
Jaspa is an unknown name to me, and I don't go for it. Sounds like someone yawning. Sort of made up warning too.