Got pm....
Just curious, why do you need longer blades?
My ultra white with 582 weighed about 330 lbs. (few lbs less with arctic cat)
I weigh 170, (did weigh 190) and I have 23ft blades and runway elev is 800msl.
It flys great, always has.
Climb is about 700fpm in the summer and about 900fpm in the winter.
I have wondered if 24ft blades would increase the climb performance.