I thought Jassman's 43 with 700's was an awesome build. That being said the 850's would be more than enough motor for the 43. I think a 1025/1075 boat would be overkill and the resale would be tough if the buyer was scared of the upcoming maintenance.

I was told the 850's get double the hours before rebuilds when compared to the 1075's.
Both need valve adjustments every 25 hours which could seem like a pain in the middle of your boating season. 25 hours could be a couple weekends of boating!