OB wot range is 5000-6000 rpm, achieves max horse power at middle 5500 rpm. It's a DOCH, not SOC engine. If already at 6250 wot rpm, OB is over revving + 250 wot rpm while rev limiter isn't kicking in.
Ideal would be for OB to run at middle 5500 wot range or at max 6000 range as loaded. If like going full throttle, over revving will consume more fuel at slight less top end speed than going at middle/max wot range. Try a 16 pitch prop to lower wot rpm towards max wot range or a 17 towards middle wot revs, only checkable on a water tets...
Will depend entirely on what you preffer : better hole shot with slight less top end speed or less hole shot eficiency with slight more top end speed. Can't have the best of both worlds on a single prop...
Happy Boating