New Proposed Blind structure for tournment on the 18th Aprill

With over 300000 chips in play this blind structure would give us a game lasting about 6-7 hours(with no breaks) is this too long? The average chip stack for the 14 players listed is over 20000,bearing in mind that in a normal tournament the first big blind should be 1/50th of the starting stack so if the average starting stack is 20000 the first blind level should be 200/400. Ive put in 100/200 as the first level this would give those with a below average starting stack more of a chance, let me know what you all think .Meet at 1pm for a 2pm start