Out of your list, I like
Lewis and
James the best. I think
Alistair and
Ernest are a bit fussy, especially combined with
Sebastian.
Other names that "work" with
Sebastian:
AlexanderAndrewArthurBartholomewBenjaminCharlesChristopherEdwardFrederickGeoffreyGeorgeGregoryJacobLaurence/Lawrence
LeonardMichaelNathanielPhillipRichardRobertRoderickThomasWilliam
You might want to consider using
Sebastian in the MN position. It might flow better.