800 film will easily tolerate a one stop over-exposure and you may like the result. It's worth a try, I think. Recently I shot a wedding on Pro400H and I threw a roll of 800Z into the bag just in case. Well, during some hectic shooting the 800Z got shot as if it was 400H (I didn't notice) and there's very little difference between that film and the other 400H rolls - perhaps a little more 'punch' to the colours.